In reply to Firestarter:
To learn to drive, I sat down with a book and studied, then I did a written test with a rather high pass grade (>90%). Only after I already knew what was going on, how things worked, did I get in a car with a more experienced person and start driving. They didn't have to explain what a roundabout was or the rules of right of way, at times they'd correct mistakes - though none I recall were life threatening but had they been the experienced person would have intervened.
Contrast that to turning up at a crag with someone who doesn't know what a top rope is, or how to tie themselves in or how to thread their belay development device. If you can have all those things squared away before hand, your more experienced partner (perhaps I wasn't clear on this bit) will validate your skills as you go without having to teach much. They (should!) know your level of experience, so with that in mind will keep a close eye on everything you do.
You can get pretty far with some reading material and a tree in the backyard. How many folks over the years taught themselves basic (and quite advanced) rope skills in a tree?
Sure, you can make a bad job of teaching yourself. Just as many can make a bad job of teaching you. Accidents in North American Mountaneering is a good read, to make sure you are aware of the consequences.
My learning was a mix of ways. Teaching yourself only fits a specific sort of person.
Oddly enough the most needlessly dangerous situations I've been in have been sport climbing with more experienced people. I suppose they had been taught by someone else, as those methods wouldn't have made it past the first editor let alone to print.
Post edited at 00:49