I keep thinking we need a way to become our own personal IDPs, then we can have both. But if too many people find the current state of the fediverse confusing we're never going to get a critical mass of people to manage their own oauth profiles and scopes.
There is a way I know of to have a federated and decentralized identity system, but it involves blockchains and will immediately draw the ire of anyone that hears the forbidden words describing it.
Did it still have that awkward immutability aspect to it? Imo that's always been one of the other major downsides to the tech for wider use cases (the others being the scalability problems that in turn contribute to the energy problems).
Imo identity is way too dynamic to make sense making immutable records of, despite so many real world systems treating it as static.