In the two other arts I practice, music and Alexander Technique, there's a clear difference between amateurs/hobbyists and professionals. There's also a clear difference between teaching amateurs and future professionals. I'm only doing the former and not kidding myself about doing the latter. The people who come for Alexander Technique lessons with me aren't planning to teach the technique themselves. The adults I teach recorder playing to aren't planning to become professional musicians. The only exception to this might be the occasional talented child - we'll see what they end up doing.
As far as I can tell they aren't telling themselves that they are as good as anybody. There seems to be a clear idea of the difference between someone who's had the professional training and put in the hours and who hasn't.
Especially in the AT lessons I'm explaining the very basics over and over again. Most people barely lean the basics, which is usually enough to solve the problem or question they came with. Then they stop having lessons. I get to feel satisfied that I helped someone solve a problem they had. If I want to enjoy talking about the finer points of the Technique, I go visit the teacher training course where I trained and work with the students there. They are busy studying the Alexander Technique every day.
If someone would come to me asking for recorder lessons with the goal of passing an entrance exam for the conservatory for example, that would be a different situation altogether. In that case I would demand much more from the student.
In aikido the situation is much more unclear because the professional training courses aren't there really. It's easy to start training at a dojo and imagine that what one's doing is the same as what the seniors did when they started, because where else could they have learned this? Especially if the seniors themselves are effectively amateurs as well, which seems to be the case in some dojo. I mean, I could start a dojo now and be a bad example to a new generation, and who would know any better?