I am sure I have been guilty of this transgression on many occasions. So - here is my defense.
First, I think we need to define what kind of interaction we are having (or expecting to have) on SB. Is it an "Ask The Experts" resource, a participatory classroom, or a public discussion? You and BoulderJohn may tend towards the former, and while I agree that much of the value of SB derives from knowledgeable experts, I also think a great deal of value comes from "Joe Layman".
Second, many of the things that experts "know", including diving experts and medical experts, are debatable or just plain wrong. Laymen who come along and question those things provide the vital impetus to re-examine old habits and conventional wisdom. In a field where diving experts find much to disagree about and where medical experts admit that there are many unknowns, there is at least a little room for amateur speculation.
Expertise is almost always developed by amateurs, to be later enshrined by experts.
My own participation on SB is intended to learn from others and, if I am lucky, to add value where I can. I try to be right, but I won't be batting 1000 anytime soon...