>Isn’t PLC tied to bluesky (or some other central authority)?
Yes, PLC is currently tied to Bluesky, and is in the process of moving out into a separate legal entity (https://docs.bsky.app/blog/plc-directory-org). It would indeed remain centralized.
>Why didn’t they use some mechanism for decentralisation, like a DHT (e.g. did:pkarr)?
AFAIK Bluesky is open to supporting more did methods in atproto in the future as long as they can act as permanent identifiers. I found a response from Bryan about `did:dht` here: https://github.com/bluesky-social/atproto/discussions/2705#d...:
>did:dht is interesting and maybe could work, for atproto, but there have been many DHT projects in the history of decentralized computing, and only a small handful have really worked out. AKA, been resilient to abuse, attacks, neglect, etc, over years and decades. magnet links are cool but kind of the exception to the rule. I think if the W3C standardized did:dht it could be a real contender, but somebody needs to carry the flag and demonstrate it working "in real life" with millions of users, and I suspect that will be difficult, and I would not expect Bluesky to lead that charge (we already have our own pet DID method to maintain and support).