he should make the platform $5/month to post and free to read. That would likely increase the quality of content and provide another source of revenue.
The reason this idea does not go far is because the people who pay usually do not necessarily post good quality content , that degrades the quality of UGC and view time therefore ad revenue loss
I agree that introducing paid accounts would make it harder for content farms to exist - primarily due to the fact that they would need a very large number of bank accounts and/or payment cards. However I don't think it's a real solution to this problem. Maybe as a part of some holistic anti-bot system? Yes, that could work.