My point was not to bring up AMMs as a solution (they aren’t) but to suggest how broad the solution space could be without having a clear winner. IMHO, if there is a large solution space and there is no obvious good-enough-for-everyone solution, it’s best for a low level of the stack to stay agnostic and let higher levels (contracts/dapps/L2s) decide what is appropriate for their use case.
Since we seem to be concerned primarily with fiat price oracle and my example doesn’t work for that, I’ll offer an alternative to make my point (but please don’t attack the solution, it’s purpose is only to indicate the non-trivial extend of the solution space): Maintain a list of credible sources and have validators relay authenticated messages from them. This could be straight-up signed messages like in the case of Coinbase’s friendly new oracles, on-chain state for on-chain sources, or recorded authenticated HTTPS transmissions. The consensus rules would verify authenticity. Happy to discuss the pros and cons of this approach, but, again, that is not really the point. More alternatives have also been brought up by others above (trusted council like MKR, prediction markets).
I’m just wondering why the proposed solution in particular is being singled out for beacon-chain-consensus status when the solution space seems to me an active area of innovation with no clear winner. It’s also not entirely clear to me what we gain by promoting it to the consensus layer, though I see a lot of the drawbacks articulated by others above.