Yet it’s normal for Mastodon users to join in on the conversation here.
Well, as neither of us are presenting or citing data on this, we can’t be sure.
Personally I care about this and keep a bit of a lookout for it and have in the past tried to advocate for and create more cross-platform talk. In my experience, and from what I’ve heard from others, the UX friction from the mastodon end makes it mostly a dead end. So while some cross talk certainly happens, I’d estimate it’s quite minor and meaningless in so far as we’re talking about it as a salient strength of ActivityPub compared to its competitor ATProto.
That’s a decision on the side of the developers, not a weakness of the ActivityPub protocol.
What this misses is whether the protocol makes it easier or harder for developers to ”decide” to allow for more inter-platform cross talk. Part of my critique was that the protocol and its general design isn’t making this easier. Kbin, for instance, doesn’t truly support microblogging. And the lemmy devs have acknowledged that allowing users to be followed like communities would be good but is just too hard right now.
The question then is whether the protocol could have made this easier for platform devs, either through its design or through providing fundamental tooling that enables developers more and removed the need for constant wheel-reinvention. From what I’ve heard from actual developers working with the protocol, they’re real technical critiques to be made around how hard it is to work with. So I believe that it isn’t helping anyone interested in making something new and interesting with it (which has yet to be done IMO, though kbin gets close ).