I wouldn’t say censorship alone is the primary motivation here so I’m a bit wary when people bring it up. But the way to think about it is that your data being on PDS is the mechanism that creates a market opportunity for other apps that, among other things, differ in moderation strategies.

Concrete example: Bluesky banned a person, and Blacksky community disagreed with that ban. When Blacksky switched http://blacksky.community app to have its own complete stack (including its own database), that person’s posts became visible there (despite them being banned on Bluesky app) because they reversed that moderation decision. This was possible because the data for this person’s posts still lives on their PDS.

In general, the data being “pulled outside” products is what enables new products (or forks of products) to come onto the scene and immediately begin competing because they don’t have to solve the “cold start” problem. If you log in, all your stuff is “already there”. And it’s the same shared world so the community doesn’t get forked. You’re just looking at the same underlying data under a different lens, and products act like lenses rather than boxes.

This doesn’t mean that “censorship” can’t exist (every layer can ban you, as always) — but it means that every layer of the stack has opportunity for competition that isn’t possible with centralized platforms. In fact, arguably, it’s more flexible than a Mastodon instance because you can’t fork a Mastodon instance “with all its users” and offer a version that reverses some moderation decision. In atproto, you can.

> I don't care about controlling my PDS if other people can't see my posts.

Isn't that similar with Mastodon? Someone on an instance that does not federate with yours will not see your posts, and I guess someone on an instance that would censor you would not see your posts?

That someone would have to change instance if they disagree with the moderation, and doing so is more painful with ActivityPub than with ATProto, right?

Disclaimer: I have no skin in this game, I don't use social networks. Just interested technically :-).

The difference between Bsky and Mastodon is that Bsky unbundles PDSes and App Views, while Mastodon does not.

Migrating to a different App View should be painless in theory (app views are not supposed to collect any state that is not saved in the PDS, not sure if Bsky does or not), and you can use multiple app views with one PDS. On Mastodon, you have to migrate both at the same time, and moving content across instances is not yet a fully solved problem.