Why Validator Committees Could Replace Single Builders

A single builder like Flashbots or bloxRoute controls transaction ordering for a massive share of blocks. This creates censorship vectors and makes the entire network vulnerable to their downtime or capture.

• >80% MEV-Boost blocks often flow through a few dominant builders.
• Chain halts become possible if the primary builder fails.
• Regulatory attack surface is concentrated, not distributed.

A centralized builder acts as a profit-maximizing gatekeeper. They capture MEV that could be returned to users or validators, leading to higher costs and a less competitive DeFi landscape.

• Value leakage from LPs and traders to a single entity.
• Opaque auction mechanics reduce trust and composability.
• Stifles innovation in fair ordering and PBS designs.

A committee of independent validators (e.g., Obol, SSV Network) collectively assumes the builder role. Security scales with participant count, not a single entity's capital.

• Byzantine Fault Tolerance requires only a honest majority of the committee.
• Censorship resistance is enforced by decentralized governance.
• Liveness is guaranteed as long as a threshold of nodes is online.

Validator committees create a competitive marketplace for block production. Revenue is shared among participants, aligning incentives and decentralizing power away from monolithic entities like Jito or Manifold.

• Profit sharing rewards committee stakers directly.
• Permissionless participation lowers barriers for new builders.
• Dynamic reconfiguration allows committees to adapt to failure or malice.

The dominant PBS model funnels >90% of Ethereum blocks through a handful of builders, creating a fragile oligopoly. This centralizes power, creates single points of failure, and forces validators into a passive, rent-extractive role.

• Centralization Risk: Reliance on Flashbots, bloXroute, and Builder0x69.
• Validator Passivity: Validators outsource block construction, losing sovereignty.

Flashbots' SUAVE is a dedicated chain acting as a decentralized, competitive marketplace for block building. It separates the roles of preference expression (users), computation (builders), and execution (validators).

• Decentralized Auction: Builders compete in a transparent, on-chain mempool.
• Committee Finalization: A decentralized network of executors (validators) commits to the winning block, breaking builder monopoly.

Obol enables Distributed Validator Technology (DVT), where a single validator's duty is split across a fault-tolerant committee of nodes. This is the foundational primitive for committee-based validation, which naturally extends to committee-based building.

• Byzantine Fault Tolerance: Requires only a majority of honest nodes.
• Natural Progression: A DVT cluster can internally run a builder client, distributing the building role.

EigenLayer's restaking mechanism allows ETH stakers to extend cryptoeconomic security to new services. This creates the trust layer for permissionless, slashed committees of block builders or sequencers.

• Cryptoeconomic Security: Builders can be slashed for misbehavior.
• Permissionless Committees: Anyone with restaked ETH can join, ensuring decentralization and liveness.

Most rollups today use a single, centralized sequencer—a clear regression in decentralization. This creates censorship risk, high latency for forced inclusions, and captures all transaction ordering value for the sequencer operator.

• Single Point of Control: Operator can censor or reorder transactions.
• Value Extraction: All sequencing MEV is captured by a single entity.

These projects are building decentralized, shared sequencer networks that multiple rollups can use. They replace a single sequencer with a committee of nodes that order transactions, enabling fast pre-confirmations and fair MEV distribution.

• Rollup-Agnostic: A single decentralized network serves many L2s.
• Committee-Based Finality: Uses HotStuff or Tendermint consensus for ordering.

Consensus among a committee introduces a deterministic latency penalty. For high-frequency MEV, this is fatal.\n- ~500ms+ added latency per round-trip for BFT-style consensus.\n- Real-time arbitrage and liquidations become unviable, ceding value to centralized builders.\n- Creates a performance death spiral where the best searchers abandon the chain.

Small, permissioned committees are prone to implicit collusion. The economic incentive to maximize extractable value (MEV) will dominate.\n- A 3-5 entity committee can easily signal via transaction ordering.\n- Replicates the Flashbots dominance problem at the protocol layer.\n- Regulatory scrutiny increases as identifiable entities control chain destiny.

Byzantine Fault Tolerance (BFT) consensus for committees creates a liveness vulnerability. A single malicious or offline participant can halt block production.\n- 33% fault tolerance threshold for safety, but >0% can stall liveness.\n- Contrast with today's proposer-builder separation (PBS), where a single builder failure is irrelevant.\n- Creates a more fragile, higher-stakes system for marginal decentralization gains.

Committee-based building explodes protocol complexity, creating new bugs and governance overhead. Compare to the relative simplicity of Ethereum's PBS roadmap.\n- Introduces multi-party computation (MPC) and threshold encryption as new critical failure points.\n- Every upgrade requires unanimous committee coordination, a governance nightmare.\n- Suave's attempt at decentralized intents shows how quickly this becomes intractable.

Running a high-performance, globally distributed builder node is capital and expertise intensive. Committee members require heavy staking, but rewards are diluted and risky.\n- $10M+ hardware and staking capital for sub-second performance.\n- Rewards must exceed running a solo builder, but committee output is inherently less efficient.\n- Rational actors will choose Jito-style auction participation over committee liability.

A formalized, on-chain committee is a bright-line regulatory target. Members are identifiable and perform a clear, centralized function—block production.\n- Transforms decentralized protocol risk into centralized entity liability.\n- Invites SEC scrutiny under the Howey Test for a common enterprise with profit expectation.\n- Creates a single point of enforcement failure for the entire chain.

Reliance on a handful of builders (e.g., Flashbots) creates censorship vectors and extracts maximum value from users. This centralizes the most critical layer of transaction ordering.

• >90% of Ethereum blocks are built by just 3-5 entities.
• Creates regulatory attack surface and protocol fragility.
• User experience is opaque; no competitive pressure on MEV extraction.

Proposer-Builder Separation (PBS) is incomplete without decentralized builders. A committee of validators, using protocols like EigenLayer for cryptoeconomic security, can act as a credibly neutral builder.

• Distributes trust across hundreds of operators, not one entity.
• Enables native cross-domain MEV capture without external bridges.
• Aligns incentives with the underlying chain's security (e.g., restaking slashing).

Commitments enable a new transaction paradigm. Users submit signed intents (e.g., "swap X for Y at >= price Z") rather than raw transactions. The committee's solver network competes to fulfill it optimally.

• UniswapX, CowSwap prove the demand-side model.
• ~30% better execution for users via competition.
• Shifts complexity from users to the protocol's solver layer.

A committee isn't just a technical construct; it's a new economic primitive. Fees from block building and MEV are distributed to committee stakers, creating a self-reinforcing security pool.

• Generates yield for restakers beyond base consensus rewards.
• In-protocol cross-subsidization can fund public goods (cf. EIP-1559).
• $10B+ TVL potential from existing restaking pools seeking utility.

Watch LayerZero and Across. Their omnichain liquidity networks are building alternative, application-layer ordering systems. If they vertically integrate block building, they bypass validator committees entirely.

• Direct user relationships and liquidity moats.
• Application-specific sovereignty vs. generic chain security.
• This is the modular vs. monolithic debate at the execution layer.

For Architects: Design for intent origination and solver competition. For VCs: Back teams building committee coordination middleware or shared-security primitives.

• Key metric: Percentage of chain blocks proposed by the committee.
• Key risk: Liveness failures from complex distributed signing (needs robust DKG).
• The window is open before Ethereans fully solve decentralized PBS.