I have no reason to think those are the options. I've experimented with much lower posting fees and some territories still have low posting fees and no one is getting that kind of engagement.

In fact, posting frequency didn't decline dramatically as fees rose from 1 to 10 to the variety we have today.

In spirit, though, I think higher fees increase signal quality and decrease signal quantity, so finding a balance is important. Prices have to coordinate many competing interests, which is why there aren't obvious one-size-fits all solutions to these problems.