“Self taught” means that they have discovered and invented knitting all by themselves!
Actually, what they meant to say was that they learned by themselves. That is, they looked through some books, watched videos, and think they learned it. These things all have teachers behind them! There is someone that wrote the books, or made the videos… except there is no feedback from the student. In any good learning experience, there needs to be feedback to measure progress and to correct mistakes and to answer questions. That doesn’t happen. So these “self taught” knitters create bad habits for themselves, without knowing it, and cause all kinds of problems.
A proper education would clear this up. Your grandmother or aunt is not always the best teacher! And you don’t need formal classes. But a good foundation is absolutely necessary… in my humble opinion. Sure would make it a lot easier for all of us.