Allowing every drive by commentator is a huge mistake in building an actual community. Communities are built by people invested in the platform.
In the early to mid aughts I was part of couch surfing. It had a lot of purpose built in friction and it created an amazing tight knit group of people that I still consider my best friends. Once the pressure from Airbnb and investment money caused them to remove that, it became terrible.
Sometime never growing a community over a small group of invested people is the right choice.
The same thing happened with NextDoor. When it was small and just involved a few hundred people in your immediate neighborhood there was a real community on there. Then the kept expanding the size and now you have people that live no where in your community ruining the experience for everyone.