On the other hand, some very successful climbers have taken pull-ups to an extreme, and seem to do well with it. Check out the training program of Dmitry Sharafutdinov (triple wold champion, bouldering world cup winner) here:
Bouldertraining: Das 700-Klimmzüge-System des Boulder-Weltmeisters It's in German, the gist of it is that Dmitry compensated for the lack of climbing facilities in his hometown by building up to extreme volumes of pull-ups. He does around 700 reps per session according to the article, 20 drop sets each with 40 and 50 kg added (accounting for around 300 reps, how he gets in the other +- 400 reps isn't specified). His 1 RM was + 72 kg at a bodyweight of 57-62 kg at the time the article was published, and and he managed 15 reps in a row with 40 kg added. What is even more impressive are the drop sets - if he could do 14 reps @ +40 kg a mere four minutes after doing 15, it stands to reason it was a fairly submaximal effort - and/or he has incredible recovery ability. Looking at the program, I'd say the main thing it does is boost work capacity. I'd reckon it allowed him to get in pretty extreme volumes of high intensity boulder problems whenever he did manage to go to a good climbing location.