Well, that’s almost still right. The nice thing about ActivityPub is that it doesn’t have to be e.g. Mastodon or even “their servers”. Nowadays even blogs can speak this, or at least enough so followers can subscribe to the “instance” that is in fact just a blog. It’s another outlet, like RSS, but has support for subscribing and commenting built in without the need to create another account. Exciting times.
Manton Reese notes when evaluating new social networks (like WTSocial I assume) he looks to these four traits…