> What if you become part of a community that has 5 users total (including the leader), should we just discard this community in the name of spam prevention?

Yeah! you even won't have to go too far to see how all this works out. Just take a quick peek to Discord or Steem.chat to confirm how all these 'communities' pans out.

*Digital spaces of live interaction & engagement which doesn't cost a damn whatsoever to create as many communities as you wish. Btw. :)*