They can get away with it. What recourse do most writers have, especially with PA holding the rights to their books? The most striking example is of an author who asked a few questions on the PAMB and was told to "cut the crap" by infocenter.
The author has continued to send PA manuscripts, money and thanks since then.
When the old guard of PA loyalists were prominent on the boards, a few of them even defended the abusive responses. One excuse given was that authors ask
boring questions, so infocenter is justified in having "a little fun".
So what's unprofessional and abusive to us is normal for them, and I think that the newer authors quickly realize that they will be either ignored or denigrated for asking questions (unless these are along the lines of "Do you take MasterCard?").