Not necessarily. Just one famous example; BitTorrent is decentralized but for most people it's just "run this app, download files". "Decentralized" just means "doesn't rely on a centralized service to accomplish a goal". As long as the application isn't too complex to install and use, most folks won't care one way or the other whether it's decentralized or not, as long as it accomplishes the goal they're looking to accomplish.
In practice this issue arise something like this: A decentralized service is launched it is so decentralized the user has to store their own private keys. Later a centralized solution is launched where the user does not have to go through the trouble of storing the private keys, everything is managed for them... everyone joins the centralized service.
In my mind, I put them somewhere in-between, leaning a tad more toward "centralized" because they still rely on an individual to host the service no matter how "federated" they are. Until they're truly peer-to-peer, there's still that aspect of centralization involved. We need something kinda like BitTorrent but for messaging / social connections.
Although Git repositories are portable, PRs, issues, actions and such aren't — so even if the migration away from Bluesky is lossy the comparison seems apt.