I do think forums, of any type, contribute to the use, excitement ,and purchases contributing to the hobby. Once you back away from the social interactions, I'd think many would settle into a more happy and/or satisfied enjoyment.
My honest answer is one. I frequently smoke one pipe for weeks or even months to test it out, as I like to call it. I own more pipes than I ever care to admit, and it's literally my job to sell guys pipes, so I'd love to say more. But I genuinely can get by contentedly with a single pipe.