Vitalik Buterin’s Two-Part Proposal Targets Ethereum Block Builder Centralization and Toxic MEV

The problem Vitalik is pointing at: the builder bottleneck

• Steer ordering to maximise MEV, often at users' expense
• Prefer certain flows, venues, or counterparties
• Comply with censorship pressures more easily than a diffuse validator set
• Accumulate privileged information, compounding their advantage over time

Buterin's framing is less about villainy and more about incentives. If the optimal path to profits requires scale, private orderflow, and proprietary infrastructure, decentralisation does not magically persist. It erodes, quietly, then all at once.

Part one: weakening builder centralisation without breaking performance

Buterin's first bucket of ideas targets the structural reasons builders centralise. While the post canvasses multiple directions, the core theme is consistent: reduce the amount of discretion any single builder has, and make it harder for scale and private deals to become the only winning strategy.

A few mechanisms typically sit under this umbrella:

Moving more of PBS into the protocol (or at least reducing reliance on off-protocol glue)

Ethereum already lives in a world shaped by proposer builder separation, but much of it is mediated through external infrastructure and norms. Buterin's proposal pushes toward designs where the chain itself provides stronger guarantees around how block building happens, with less dependence on a small set of intermediaries. ^[3]

The practical objective is straightforward: keep the builder market contestable. If new builders cannot realistically compete without bespoke connectivity and relationships, the market stops being a market.

Constraining what builders can censor or reorder

One of the most worrying properties of centralised building is not just who captures MEV, it is who can decide what does not land onchain.

Buterin's discussion points toward tools that would make censorship harder, such as requiring inclusion of certain transactions (under defined rules) or reducing the latitude builders have over the full contents of a block. You can think of this as pulling Ethereum back toward a baseline guarantee: if a transaction is valid and paying fees, it should not need permission from a small club of block engineers.

Increasing credible neutrality at the block construction layer

Neutrality is not a vibe, it is an engineering constraint. The more a builder can selectively privilege flows, the more Ethereum starts to resemble a permissioned ordering service with extra steps.

Part two: going after "toxic MEV" and the sandwich economy

This is the flavour of MEV that makes normal users feel like Ethereum is running a toll booth they did not agree to. The post's thrust is that Ethereum should not treat this as inevitable.

Limiting pre-trade visibility

If pending transactions are fully visible, MEV searchers can simulate outcomes and insert their own trades in front of yours. Approaches that encrypt, delay, or otherwise shield transaction details until ordering is locked can blunt front-running and sandwiching.

This is not "privacy for privacy's sake". It is about removing a mechanical exploit: seeing the future a few seconds early.

Designing execution paths that are harder to game

Another route is to change how trades reach the chain, for example through batching, auctions, or other mechanisms that make it more difficult to surgically target individual transactions. These designs can reduce the profit available from toxic strategies, even if they do not eliminate MEV entirely.

Market read-through: ETH trades the narrative, but the roadmap is the real catalyst

Ethereum was changing hands around $2,033 at the time of CoinDesk's report, roughly camped on a psychologically important $2,000 handle. Price is not the story here, but it is the scoreboard traders stare at.

The more relevant market impact is second-order:

• Stakers and validators care about how any redesign might affect proposal rewards and MEV capture.
• Searchers and builders care about whether their edge is being regulated by protocol design.
• DeFi power users care about execution quality: fewer sandwiches means better realised pricing.

The uncomfortable trade-offs, and what could rug

This is where the dry British understatement comes in: changing the block-building pipeline is not a weekend refactor.

Key risks and tensions include:

• Complexity risk: More moving parts at the protocol layer can introduce new failure modes.
• Latency and throughput trade-offs: Some anti-front-running techniques can add delays or reduce composability if done poorly.
• Builder incentives: If you squeeze toxic MEV, you may also squeeze legitimate arbitrage revenue. Builders may consolidate further if only the biggest players can adapt.
• Migration risk: Any shift away from today's tooling can create a chaotic interim period where execution quality worsens before it improves.

Also worth saying plainly: MEV is a hydra. Kill one head, another appears in a different venue, rollup, or orderflow channel.

What to watch next (checklist)

• Specification signals: does this remain a conceptual blog post, or does it crystallise into an EIP track with concrete timelines?
• Builder concentration metrics: watch whether the share of blocks produced by top builders narrows or widens as the conversation heats up.
• User-experience indicators: changes in sandwich frequency, average slippage on major DEX routes, and reports from wallet routing providers.
• Validator economics: any meaningful shift in proposer rewards, MEV tips, or variance in block payouts.
• Infra alignment: whether major clients, relays, and builder stacks publicly support specific designs, or quietly resist them.
• Regulatory and censorship pressure: proposals that reduce censorship power become more urgent if external pressure on intermediaries increases.

Ethereum has always been a machine that upgrades itself mid-flight. Buterin's latest post is a reminder that decentralisation is not a static property, it is a maintenance job, and the builder layer is overdue for a service.