Why Full Danksharding Uses Proposer-Builder Separation

PBS is an economic prerequisite. The core scaling of Danksharding is a massive increase in data availability (DA) capacity. A single validator cannot feasibly download and attest to 128 data blobs in 12 seconds. PBS creates a specialized builder market that handles this load for the proposer.

Without PBS, decentralization collapses. If a validator must process all blobs, only the wealthiest entities with hyperscale infrastructure can participate. This recreates the mining pool centralization problem from Proof-of-Work. PBS separates block building from proposing, preserving validator decentralization.

Builders become data wholesalers. In a PBS regime, builders like Flashbots SUAVE or EigenLayer operators compete to construct the most profitable full block. They purchase blob space from users and rollups like Arbitrum or zkSync, creating a liquid market for block space.

The bottleneck is market formation. The technical spec for data sampling is solved. The unsolved problem is bootstrapping a competitive builder ecosystem that reliably supplies full blob data. Without it, the network's expanded capacity is theoretical.

Block production is a market. PBS formalizes the division between the entity that chooses the block (the Proposer) and the entity that constructs it (the Builder). This separation is necessary to manage the immense computational and capital requirements of building a Danksharding block, which bundles thousands of blobs.

Builders compete for profit. Specialized actors like Flashbots, bloXroute, and mev-rs use sophisticated algorithms to aggregate transactions and extract MEV. They bid in an auction, paying the Proposer for the right to have their block included. This competition drives block revenue to the validator set.

Proposers are passive auctioneers. A validator's role simplifies to accepting the highest bid from the Builder market. This trusted execution environment (TEE) model prevents proposers from censoring or frontrunning transactions within the block they did not build, a core credible neutrality guarantee.

Evidence: Without PBS, the hardware and data requirements for a single validator to build a Danksharding block would be prohibitive, centralizing block production. The existing PBS ecosystem on Ethereum, via mev-boost, already processes over 90% of mainnet blocks, proving the model's efficacy.

Committee-based sampling fails at scale. A single validator must download and attest to the entire 128 MB blob. This creates a centralizing bandwidth requirement that only a few professional stakers can meet, undermining decentralization.

Delayed inclusion is a UX poison pill. Requiring users to wait for finality after a transaction is antithetical to the real-time settlement expected by dApps and users. This model is a non-starter for DeFi protocols like Uniswap or Aave.

PBS decouples the roles. It allows specialized block builders to handle massive data assembly, while validators only verify small proofs. This is analogous to how rollups like Arbitrum separate execution from consensus for scalability.

Evidence: Without PBS, the minimum viable hardware spec for an Ethereum validator would skyrocket, centralizing the network around entities like Lido or centralized exchanges, which defeats the purpose of a decentralized data layer.