Why is it a bad idea to trust Internet climbing advice on its own?
The short answer is, Because you cant possibly know the source, and whether or not he or she really understands the subject. The long answer includes that and a few more things. Even if the source is unimpeachably knowledgeable about climbing, written communication has inherent flaws. Tone, body language none of them are possible over the Internet. In most cases, you also dont get visual aids, and then, theres the fact that very few learning methods can substitute for hands-on experience. If you already have some experience, then you and the person with whom youre conversing may share a common context that negates that principle, but then again, maybe not. You wont go wrong by supplementing your Internet-gained knowledge with questions to experienced people in the real world, books, guided lessons, etc. But you may go wrong by NOT doing so.