I necro-posted this #SocialHub topic I started long ago about "Community has no Boundary". We must design for community. Just connecting #ActivityPub apps randomly to a microblogging experience is not a way to get there.
Forum software may offer great Community support, but once you federate and connect into a microbloggoverse that whole concept of community is severely impacted.
Design for community starts with discovering Needs and objectives, and going from there.