Um yeah actually we sometimes do. Being nice won't kill anyone.
Would you like to point to 5 threads on the vB support boards that are semi-recent that discuss, in detail, the "competition"? They were civilized discussions between people that consisted of 95% vB junkies and 5% others, and yet somehow, someway, the thread didn't get closed, no one blew their top, and no one slammed competing products. That's my whole point. The attitude that exists both here and at IP is horrendous. You can't discuss the merits of one product versus another because you even mention another product and the thread gets closed and you get banned. Did anyone stop to think that if they were helpful instead of *****y that maybe someone might keep that in mind if they were looking for forum software, and think "Hey, those guys at xxx company were nice, maybe I'll see what their product looks like". Not everything revolves around sales right here and now. You have to think in the long-term, and not burn future bridges (I feel a country song coming on :D) with potential customers, or people who are customers who happen to own other software too.
I have 2 UBB licenses and 1 vB license. I bought the UBB licenses last year, and now I really don't care much for the UBB, but that's my opinion. If someone asks for help with it, I'll try to give them a hand, whether it's here or at vB's support forums or somewhere else that I happen to be.
I don't think your examples really hold any weight. This is not a pay-per-incident tech support line, it is a fan-based hacking community. All of your examples involve situtations where money is involved; where you're purchasing a product or service (or calling a specific tech support line) that is exclusive of other competing products by nature. There is no "chit chat" support line for MS or Adobe. There is a rather large difference between calling MS and asking for support with Red Hat and posting a message here in the chit-chat forum asking what happened to someone who happened to write some forum software.