You're making a very common fallacy here. If the feedback is accurate, then it stands alone. It doesn't require the giver of the feedback to prove anything.
I'm repeating this example again but one of my teachers was a famous concert pianist. He was admired by a lot of students and the other piano teachers because of his reputation. Whenever he gave instruction, his students obeyed without question. Even after months of practice didn't appear to help them improve, they blamed themselves for their failures. Even when they injured themselves to the point where they had to bandage their wrists and see doctors (this happened to more than one student, btw) they still obeyed. In fact, almost all of the piano related injuries occurred with only his students. But worse than the injuries was the fact that, in comparison to the other students of other teachers, they didn't improve much at all. In time, some of his students changed studios.
The point of this story is that just because someone has proof of his or her prowess doesn't necessarily mean the advice he gives is gold. Just like some of the advice you give I know to be useless, many of the students believe you because of your "proof". Again, the proof is in the pudding. If they don't improve after following that advice, then that advice has very little merit. Caveat emptor.