I've seen this several times in shooting.
You have champions who can't teach, and instructors hanging out their shingle who are no where near the top level.
It's hard to criticize a champion, so sometimes you won't get an honest appraisal of someone's teaching ability if they are top notch.
On the other hand there are scores of instructors out there, in any discipline who make a solid living teaching newbies and inventing status.
We call them "Gun Store Commandos" but it would be like going in as a rookie to the local pool room, some guy telling them a $500 Mali was the be all end all of cues all the champions play with, and then offering lessons for $50 an hour when they can't break out of APA 4 level.
No, you don't have to be a champ, and being one does not mean you are a good instructor.
I've been a professional instructor in several different jobs, from teaching managers at a restaraunt, to flight instruction, to overseeing a variety of training programs and doing small arms instruction to military and compatition shooters.
When you really work at being a good instructor, you learn that there are many different learning styles, and you need several different teaching styles, and eventually you realize tyou cannot reach every one. Some student / instructor pairings just don't work.
Find someone that has techniques or theories you respect, and a style you can learn from. Otherwise you are wasting your money and time.