I do agree with the management issue, but to a degree stores can drive sales. If the store manager's bias causes him to always badmouth a specific product, only stock the bare minimum of that product, and not realy make it apparent that he has that product at all... It's going to lower sales of said product at his place at least.
But then again he was in the end a bad salesman... He badmouthed 4e, but then didn't end up selling the person ANYTHING.
Similar experience, but going back to 3.5 even. The owner of my FLGS knows bupkis about RPG's (he is a model train guy) - I went in to ask whether he had Monster Manual V in during the week it was due. He says he doesn't know, calls over his "RPG Expert" who proceeds to go on a conspiracy theorist diatribe about Hasbro, and tells me they won't have it for several months, if ever (froth, froth).
They got it in the next week. I had of course already bought it from the local Barnes and Nobles.
I can understand not liking the product, thinking/hoping it won't sell, and refusing to stock it. But stocking it, then badmouthing it? Bad business. But then again, I don't see too many FLGS owners on the cover of Forbes.