For something like the 4670, sure. But for high end cards, you can't even find them in most retail stores. Those buyers are most definitely checking out online reviews and forums.
I meant for both mid and high cards. Actually for mid they might just check a box or something at dell.com and not even have much of a choice. I never forget one of the shocking tidbits that arose from the BFG bankruptcy about how they sold 10 times more power supplies at Best Buy than they did Newegg. And BFG was not a bottomfeeder PSU company, either, those were higher-end units.
As for high end stuff in particular: you'd be surprised. If all rich people spent so much time on forums and stuff, there would be a lot fewer Alienware-like companies. Some people just want "the best" and throw money at whoever has highest performance. They don't spend much time if any in forums. That's why we see such big premiums on halo cards. You see this going on with more than just PC components, too... like cameras or even HDTVs and cars, which cost a LOT more than graphics cards. Lots of people do rudimentary research for cars, like reading reviews, but actually go into car forums to talk shop? Eh... probably not. Lots of people just want some really high end gear and throw money at the problem, without actually sitting down and comparing stuff carefully, let alone reading reviews or going into forums.
Let me put it to you this way: think of a subject you don't know much about that you have already bought. Maybe a watch or something. How much research did you do? Chances are, either none, or maybe reading a few Amazon reviews, or if you were really diligent, reading Consumer Reports or a trade magazine review or something. I bet you didn't go into a technical forum online. If you did, congratulations, you should be like, a tax accountant or something.
The people at this forum are self-selecting. Remember that. Many gamers can't even be bothered to buy a video card at all; they have long since moved to consoles.
I will say that this is certainly not true at all:
This forum is many things, but a laughing stock it is not, and one of the best sources of discussion and information anywhere.
I can think of a laughingstock forum, that begins with an A.