I think "offer unlimited but ban people who are extreme enough outliers" is actually a pretty normal way that things work instead of "raise prices until equilibrium is reached", including in credit cards. Credit cards do simply ban people they think are "rewards churning" based on a completely subjective TOS policy for example.

Raising prices is a bad strategy if you have a smaller base that costs enormously larger. "A million users that cost $1 and one user that costs $10 million, charge everyone $10 equilibrium", you're screwing over almost all of your users. The $20/month sub price is basically just not trying to capture the openclaw users.