Yes I thought about that a lot with #Smithereen. Mastodon doesn't address the problem of "you've picked an instance and signed up, now what" in a way most people would expect it addressed. It has public feeds and puts a great emphasis on an instance being a community. Which doesn't work very well in practice because people want to participate in many communities and having a separate account in each is too much of an investment.
@af @sengi_app
So Smithereen reduces instances to merely underlying infrastructure that gets out of the way as much as possible. You don't think much about mail servers when you send an email, and I want the same here. For communities, I have actual groups with walls in them (and more features to come in the future). You can join as many groups as your server could handle. Joining and leaving groups has basically no cost.