How is it any different than a centralized social media service then? Merely the fact that you can get a firehose from the website in a standard format? This was already the case with HTTP. The problem is that websites can leverage their power to make a locked-in ecosystem.
see https://www.youtube.com/watch?v=BxV14h0kFs0 twitter, etc once had a much more open API. so did reddit. This was just the first stage of their penetration strategy.
The decentralization is totally irrelevant due to the way it's implemented. The problem is that Apps are sticky, so app developers have undue power to control their users.
The "content hosts" "moderators" etc need to be completely cut out of the picture to be at the same level of censorship resistance as an RSS-shared blog. I can host a blog on my own computer, and you can subscribe to it without that many intermediaries.