I personally love the way the .Zip admins handled it, both for Lemmy.zip and Piefed.zip. Defederate a very short number of instances (https://lemmy.zip/instances https://piefed.zip/instances?filters=blocked ), hide new joiners unfriendly instances by default for new users onboarding, but still allow people to unhide it.
We’ve also now enabled a similar welcome message and instance block system to what we’re running on Lemmy.zip. This means some of the spicier instances are blocked by default, which users can remove themselves in the user settings.
https://lemmy.zip/post/50200106
That gives enough freedom to power users while still being welcoming for new joiners.
Also, is there any centralized forum that is more active than the Threadiverse (Lemmy/Piefed/Pylova/Mbin)?