Surprising how many people are misreading the comment/question. Responses range from people answering the question, "What is ActivityPub?", to "What is Mastodon?"
To the original commenter: yes. This project is using ActivityPub kind of like RSS. Since it's ActivityPub and not merely RSS, the experience when using e.g. Mastodon as your reader, however, is "like RSS, worse". On the other hand, since it's ActivityPub, it also supports all the ways to track followups/replies/threads both from the original poster and people who are not the original poster, a way to dynamically track/display who else is subscribed, and it advertises a channel for you to send notifications to if you yourself wanted to reply or follow. This is its main value proposition—mostly for people who prioritize the gimmick of modern-ish social features over simplicity and economical setup/hosting.
I kind of get lost with the ActivityPub/Fediverse story. When I subscribe to a blog's RSS feed, it's a decentralised and anonymous way of "following" the blog.
Now if the blog uses ActivityPub and federates with Mastodon instances, then it's not a blog anymore, right?
Or similarly, if Lemmy is supposed to be like Reddit, then it should not federate with Mastodon (everything that federates with Mastodon kind of becomes a Twitter alternative, doesn't it?).
ActivityPub is a common language that allows describing "actors", "activities" and "objects" -- and as such, can describe any kind of social platform, from blog, to forum, to social media site, be it for photo sharing, video sharing, or something -- in your words -- Twitter-like. Not everything that uses ActivityPub will be 100% identical in user-facing functionality and UX, but most platforms have a concept of subscribing to other users, receiving new posts, and replying or re-sharing posts, which is where the interoperability comes to shine.
If your blog uses ActivityPub, it is still a blog. People could just subscribe to it to receive your posts in their home feed, reply to them, or re-share them in a way your blog could process (or choose not to).
To the original commenter: yes. This project is using ActivityPub kind of like RSS. Since it's ActivityPub and not merely RSS, the experience when using e.g. Mastodon as your reader, however, is "like RSS, worse". On the other hand, since it's ActivityPub, it also supports all the ways to track followups/replies/threads both from the original poster and people who are not the original poster, a way to dynamically track/display who else is subscribed, and it advertises a channel for you to send notifications to if you yourself wanted to reply or follow. This is its main value proposition—mostly for people who prioritize the gimmick of modern-ish social features over simplicity and economical setup/hosting.