With a #DID derived from a secret key you can truly own your identity. Unfortunately, key rotation is not supported, and if you lose your key, you lose everything. This can be partially mitigated with distributed key generation techniques that make key recovery possible if only M of N shards are available, but they are complicated.
Servers can rotate keys, but they can also suddenly disappear, and again you lose everything.
Blockchain-based systems support key rotation and don't have a single point of failure (if done right). Sometimes they are called "servers with superpowers". However, popular ones are not suitable for the job because writing to them is very expensive and their clients need powerful computing devices and a lot of storage.
Is there a way around that? Yes. Blockchains can be very lightweight and they don't actually need a cryptocurrency, miners or stakers in order to work. There is a simple consensus algorithm known as Proof of authority, and one of the Fediverse competitors, Bluesky, seems to be planning to build such system:
>We are actively hoping to replace it with or evolve it into something less centralized - likely a permissioned DID consortium.
They are afraid to say the B-word, but "permissioned consortium" is exactly what it is. Of course, their identity #blockchain doesn't have to be the only one in existence. I think in the future we might see quite a lot of "identity cooperatives" of different shapes and sizes. Perhaps even a universal client, curl for identity, can be developed.
