Funny, I was the complete opposite. General mountaineering to alpine climbing to cragging to sport climbing, and now I have a gym membership. Looks like natural selection has my number. Man I still am so suck though. I just can't overcome the ability to pitch off hard (for me) sport climbs where before I would have died. Choss puts you in a particular mindset I'm afraid.
I learned from some very gracious experienced climbers who took me under their wing and put up with my slowness and fear on routes at the edge of my ability at the time. I can never thank them enough for this and feel very lucky. I think the mountaineers and mazamas, as much as I throw out the jokes, are good for those who want to ease into a game that from an outsider's perspective, is very scary and intimidating. Not everyone wants to make climbing their #1 activity. Not everyone wants to climb the tough routes. There are also some damn good climbers involved with those organizations. Unfortunately, many of them get buried in the the inane technicalities of climbing (which direction should tandem prussiks be oriented, etc) and not the pure spirit of the activity. Unfortunately, many of these same individuals feel it is their mission in life to let you know how things should be done too. I have been chewed out by a number of them myself. I just bite my tongue. Lashing out at them will not change their minds.