OF isn't going to change anything with agencies until it starts hurting them. As you said these agencies are making a shit ton of money for themselves and OF. It's not as if the girls who actually own the page would put in the effort if they banned agencies. Otherwise, they would be doing so already. Anyone getting scammed by them at this stage should know that they are buying from an agency page. It's very easy to spot nowadays.
But the lonely and desperate whales will keep coming back and giving these agencies their money. They believe that 19 year old Jessica from LSU is constantly on her phone, talking to them, and they hope that by spending and talking, they'll eventually be together. In reality, it's really a randy Andy from India or eastern Europe calling him daddy and telling him how much she loves him.
This practice is genuinely messed up because it preys on vulnerable men who are lonely, desperate, lack self-confidence, and suffer from mental illnesses. It draws them into these parasocial relationships, they believe that a real connection might develop. Instead of trying to help themselves they think she's the one maybe something might happen, maybe we might end up together and just keep digging a deeper hole. It's how dangerous stalkers are born.