I used to play on an adult only whitelisted minecraft server. It was setup in such a way that day-to-day gameplay was as close to pure vanilla survival as possi

I used to play on an adult only whitelisted minecraft server. It was setup in such a way that day-to-day gameplay was as close to pure vanilla survival as possible. Of course the adult part is really hard to enforce so the owner took a very interesting approach to it. Anyone could join the server but you would be put in spectator mode i.e. be unable to interact with anything but just tour the builds. Then you'd have to make an application that would be manually approved between 24-48h later. Just that delay was enough to weed out the impatient. See the problem was not about the age specifically but rather childish behavior. So by realizing that we targeted the most obvious one( being impatient) and had great results. So yea, making something deliberately harder to use might be just enough.