The interesting thing about Mastodon for me is that for the time that you engage with it, it responds. When you stop, it moves on to others. There's very little residual effect. So you can basically pick it up, get a conversation going, but then you can leave it alone for a while and your presence fades away.
@triptych there's also https://a.gup.pe/ which would be the equivalent of groups, but there's nothing on our shared interests out there. It's easy to start a new group, but then we'd need to continuously fill it with content