They've been puttin' that thing out almost as long as I've been climbing. My climbing friends and I studied the first edition assiduously. There was hardly any good information available at the time, and we were teaching ourselves from what few sources we could find.
The American Alpine Club published something by Kenneth Henderson---Handbook of American Mountaineering I think it was called---that was, by and large, disastrously bad. There were pamphlets on belaying by the Sierra Club which were actually useful. There were some outdated and peculiar British books touting the advantages of nailed boots over "rubbers," and recommending the Tarbuck Knot for tying in. I think one of these was called On Climbing. I recall a French text by Edouard Frendo that recommended manila ropes over nylon for their superior resistance to cutting. It was a jungle out there.
We might not think the information in Edition 1 is all that great now, but it had an air of sanity about it that was in short supply in some of the other treatises.
Perhaps one of the advantages, in a funny way, of those years was that there was so much obviously bad information out there, that we rapidly acquired a healthy scepticism about the recommendations of "authorities," something which served us well as time went on.