gedunk once bubbled...
Almost ten years of certifying students who also go on trips and get compliments from the boat operators and DM's is my acid test. Many of these people are my friends and family and have gotten along fine and most were taught, initially at least, from the bottom of the pool, years before GUE even existed. How do you explain that?
It's easy to explain. Even if you start then on the bottom (which from experience I don't think is the best way) you can still get them off the bottom eventually. As long as you teach the skills and provide enough time for those skills to be practiced wou'll end up with a good diver. There's more than one way to do everything.