I would think this all this is perhaps a personal preference on a given instance, but not practical on a global scale.
If an instance owner wants to accept the risk of a chaotic, unmoderated space on their server so be it. Other instances are quite capable of blocking a comm or defederating if it's an instance wide problem.
There's also the potential to blockade new comms on small instances when I think of it here. If I, as an admin of a single person instance, try and set up a few niche comms for personal interests and they where report-bombed by people just being trolls, there would never be a way to get them off the ground. You would spend all your time responding to reports rather than creating content in order to avoid them being locked.