There are so many documented gains on multiple P.E. sites that this claim is simply ridiculous. I am really sorry that you haven't gained man, that sucks, it really does. However, if you are willing to actual chill out with the attitude there would be a lot of people on here who could probably help you figure out why YOU specifically haven't gained and help you overcome that barrier.
People are not pissed about you saying gaining isn't possible, people are pissed that you would come here just to try to call everyone a liar. You are challenging the character of everyone present here, that's why it ruffles feathers, not because they aren't confident in their gains or because you pulled back the curtain on some massive conspiracy to sell us all a lie (because you're oh so much wiser than us all).
Your logic is tragically flawed, in that you believe that simply because YOU have not gained, nobody can gain, or has gained ever. You come here simply to try to ruffle feathers, and to piss people off intentionally to make up for the fact that you have not had the same results, and in the hope that this will help you feel better about your failure. It won't, you're wrong, and it does in fact make you appear like a "prick" (as previously stated).