This isn't true at all. An "advanced diver" isn't qualified or trained on how to teach skills and how to evaluate students. Being a super duper advanced master diver extraordinaire has not relationship to being qualified to teach any skill at all. Few years ago, one such "advanced" diver tried to teach his buddy how to dive and only managed to hurt his buddy so he can't dive for the rest of his life (middle ear injury). Similar scenario about twenty years ago, a father tried to teach his son the basic diving skills in their 8 foot swimming pool in NY, the son almost drowned and was taken to a hospital and had to under go medical treatment. The son was traumatized after this ordeal and never wanted to dive at all.
I certainly don't want to be the buddy or the father dealing with my son's or buddy's injury because of my mistakes and doing something I wasn't authorized and qualified to do. The weight of the guilt and shame is way too much to bear.
If you don't like how a professional does their job, find another one to do it for you, don't try to do it yourself especially when you aren't qualified to do it.