And what does this revocation accomplish? The app still has your unique address. This revocation is simply "don't log me in next time." You still need to use the app to delete any data, if that's even possible (highly-dependent on the app). This is no different than going to your GitHub account (in the parent comment's example and revoking https://docs.github.com/en/authentication/keeping-your-accou...).
Only if the web3 app itself is entirely decentralized, doesn't implement any moderation, and never votes to change the above. I suspect they will quickly need moderation, and therefore it wont matter if your identity is irrevocable as the platform itself could easily block it.
I do see the value in being able to bring an identity around and store it in a blockchain, but... extreme fragmentation is a bummer.
I don't disagree that having a keypair on the client for authentication is a cool idea, but it's hardly specific to "Web3" (e.g. https://developer.apple.com/documentation/authenticationserv...).