And an hour or two to stand it up, and a domain name, and an email host since you have to respond to abuse@.

A new subreddit is two minutes and there is no reason why a federated system has to be markedly harder.

An instance is not a replacement for groups, and it's most definitely not similar to a Reddit community.

What you want is, well, "groups" which is a feature that GNU Social had, and which is eventually going to come to Mastodon and Pleroma.

A lot of people seem to happily use Twitter which also doesn't have a concept of groups.

I wish Plethora had a solid docker-compose available officially because the current installation method is not great.