Of course it isn't and I would hope that most people do.  I do on the rare occasions when I ask a question and get a helpful reply.

Maybe the less polite are those relatively new to ebay and don't appreciate how much time some members spend helping them.  Also it doesn't help that there has been a big problem with questions posted on ebay over the last month or two and the questions are ending up on various boards rather than the one they are supposed to be on. Ebay are supposedly looking into why this is happening but I'm not sure that his problem is completely fixed yet.    It is entirely possible that some newcomers can't even find the question they asked and so may not see the answers.