because the admin is tired of dealing with assholes on the internet.
You know another way to not deal with assholes on your instance? Charge just enough to make sure that people are minimally invested, and point them to the Terms of Service as the reason they are getting kicked out for egregious behavior.
maybe preferably, better tools need to be developed
If better tools was all that was missing, Big Tech would develop them and get rid of all these nasty meat bags. And as much as Google tries to do just that, they still hire tens of thousands of content moderators around the world for YouTube.
You have soup kitchens all over the world, the volunteers working for them do so because it gives them meaning,
The fact that things do not have a price do not mean that they are free. Somebody had to pay to get the food done and the volunteer can not take the hours worked in a kitchen soup and exchange for a discount on their electricity bill.