Adam Mosseri:
Second, threads posted by me and a few members of the Threads team will be available on other fediverse platforms like Mastodon starting this week. This test is a small but meaningful step towards making Threads interoperable with other apps using ActivityPub — we’re committed to doing this so that people can find community and engage with the content most relevant to them, no matter what app they use.
One way I can think of is by being such a big player that they dominate and can thereby exert their will. For example, lemmy.world is the largest lemmy instance and we’ve seen a few communities on other instances dry up in favour of the ones on the big server. Now imagine that server is a hundred times bigger than the next largest and the people in charge have an active financial interest in moving people to their platform - if they play it carefully (and I’m sure they’ll be employing people to think about how to do this) they can shift the existing content into a place they can control it.
That doesn’t really apply to Lemmy’s content though, since unlike Lemmy.world, Threads users won’t be able to create /c/ communities. If a Threads user wants to post to a community in a way that Lemmy recognizes them, they’ll have to post it to one under a Lemmy instance’s control, or Lemmy users won’t see a thing.
That was just an analogy, I believe Threads is targeting federation with Mastodon rather than Lemmy