I go to a panel discussion to hear the panel members’ opinions – not the audience’s. The audience contributes questions, not their own opinions, which is a concept that many attendees did not seem to grasp. (Exceptions, of course, for notable authors or professionals who happen to be in the audience.)
Having moderated very many panels in my time, I’d be the first to admit that there are audience members who need to be restrained from expressing their opinion interminably. However, that’s a small price to pay for a community that values discussion. Being a famous author does not automatically give you a monopoly on knowledge or wisdom. And if Worldcon ever becomes a convention where the point of attending is to worship at the feet of celebrities I for one will stop attending.