For me it's not shredding the skin that's the problem (my skin has toughened up due to climbing frequently), it's ligament damage. Basically this: http://en.wikipedia.org/wiki/Climber%27s_finger It has been doing a tour of my fingers recently, had it on most of them at this stage, luckily only in the milder annoying form, not the serious crippled finger form.
Outdoors is excellent fun, much better than indoors, I try to get out when the weather is nice.