Or maybe people were willing to give something a chance, and found that though it has benefits, it's not everything it's cracked up to be? I am a solitary person so I found the entire idea of pair programming repugnant but some people really love it. I don't think it has anything to do with fashion more to do with what some would consider a failed experiment. Did coding this way yield quality code at a faster rate with less stress? Anecdotally I would say no, and that may be why it's called nonsense by some.