Yeah, I'm serious. Even with Twitter, for example, currently allowing accounts to be created and posts to be made for essentially free, real accounts and posts still outnumber those of troll farms and bots from what I've seen. If those troll farms and bots actually had to pay, I imagine there would be far less. I also imagine that those troll farms and bots are less influential than real people. I believe that the endgame is that if a website operator takes enough measures to stop troll farms and bots, the operators of those troll farms and bots will eventually run out of resources and be forced to curtail their activity.

You're right that gating speech behind money could potentially be bad and make problems worse but I only offered that as one suggestion. Instead of or in addition to using money, you could perhaps make a system that uses some type of karma/reputation for instance. Those could still be done anonymously.