".. the talks are all about the platform Bluesky and not about the protocol."

The point is that there's no functional difference between the two. BlurSky controls the protocol. Even if they didn't, they control the ID layer of the existing network.

When Gab and Truth.social tried to join the fediverse by setting up servers with Mastodon forks, and Threads by implementing ActivityPub, all fediverse servers could talk to them. Admins opposed to that had to campaign for other admins to block them, server by server. Those of us who saw benefits in people on those servers having access to other perspectives could argued against blocks. Each server's community could make its own decision, based on their own values and needs.

If they tried to do the same thing by setting up servers with BlueSky forks, or implementing ATProto, BlueSky could just ban their ID range from the existing network. For some people this is a feature, not a bug. But it's not decentralisation in any meaningful sense of the word.