How do defend Ethereum from the threat of retroactive bribes?
Airdrops can be used for retroactive bribes. Building on the OP’s example, imagine a de facto natural monopoly is created around Metamask’s invoker contract post EIP 3074 getting in. This could logically follow from the circumstances without any nefarious intentions: invoker contracts are extremely security sensitive, so it would make sense for Metamask and other wallets to whitelist them with extreme prejudice, to avoid users being tricked into delegating their wallets to a malicious invoker. As the largest EOA wallet Metamask’s invoker is likely going to get the most traction. It will have the largest AUM. The larger its AUM the more trusted the contract is going to be, because the AUM serves as a natural bounty. The larger the bounty, the more confidence we can have the contract is safe, because the incentive to compromise has not materialized.
It would be safest for this contract to be immutable, and I’m hoping this turns out to be true for the first versions of it, given the security implications. But let’s consider what happens if down the road, after enough confidence has been built up, an upgradeable version of the invoker contract is launched. Naturally, you couldn’t have the upgrade capability controlled by a centralized multi-sig. That would be unsafe. So we could end up with a governance token. One that controls one of the most important contracts in the ecosystem, with the largest AUM other than the beacon chain. It might be worth a lot. Maybe billions. We’ll have airdrops, possibly rewarding everyone who supported the consensus changes required for all of this to happen. They would be celebrated as retroactive grants for public goods instead of a reward for promoting a special interest. Nobody has to even promise anything in advance or act in bad faith. The incentives around this are similar to the revolving doors between government regulators and private industry. The expectation of a lucrative high paying job after your public service ends can be enough to align those working in the public sector with the private sector. No bribe needs to be offered or accepted. No laws broken.
The possibility of using airdrops this way makes it harder to protect governance against special interests. I am a little reluctant to point this out but probably this is something those working to promote special interests are smart enough to figure out for themselves. I’ve come around to thinking it is better to talk about this openly so we can think about possible mitigations and have the motivation to implement them.
A conflicts of interest section in the EIP might help somewhat. They’re standard in the academic world. In the meantime, until we make that improvement to the EIP process, perhaps asking openly anyone who is campaigning for an EIP whether they have any upside (eg equity) or expectation of receiving upside (eg informal promise) to the example outcome?
Exposure or expectation of upside wouldn’t necessarily be a dealbreaker that makes your arguments in favor of an EIP invalid, but the extra information gives the other participants in the discussion the ability to account for the possibility of some motivated reasoning being in play. We’ve done this implicitly for things like EIP-999 but it isn’t always going to be that obvious.