In reply to Michael Gordon:
That's what I though when I first started, but of those I've seen in traffic on a busy climb, quite a few were doing something dumb (sloppy technigue, moving up in the fall line of ice lumps from climbers above, climbing over others ropes without proper care, etc). On my Tower Ridge ascent I had to go almost into meditation on Tower Gap to calm down: the last in a group of soloists who was plain ignoring me and messing with my ropes despite me asking him just to wait 30 seconds so I'd be safely on belay, then tripped on stepping down into the gap and caught a sling on my rope to stop a fall. You could almost question why any sensible soloist would be on the main line on Tower Ridge on a good day when many parties are visible above and lots of other routes or variations on the main ridge line on that route were clearly free.
Still compared to some of the popular big routes in europe the commonality of such incidents I've experinced are less. I dont expect everyone to be up to the standards of the best I've seen and climbed with (a certain P. Holden would be an example of amazing crisp technique)