"just don't read them if you don't like them."
I think that the Cuban knows that, but it is a pain in the ass. He probably wants to reserve PM to talk to who HE wants to talk to, if you have a question email him. As a very active member of the board, it can be a pain in the ass sometimes to talk to who you want to without trying to amswer 50 questions from everyone else. When you email a mod or a vet, they can answer the question when they have time.