That's not really relevant to what I said. I said knowing/learning theory won't hurt you. You can teach yourself theory. Everything you just said has nothing to do with theory, it's just about if someone gets a bad teacher...
My point is, learning theory does not equal understanding the vibrations of the universe and how they affect human consciousness. It is merely one way to contextualize a small subset of our understanding of the universe.
For instance, there are theoretically infinite tones. Yet we arbitrarily restrict ourselves, generally in the "western" mindset, to just twelve. And thus, many are led to believe that an arrangement of sounds outside of those twelve tones is inherently "unmusical."
What I'm trying to say is that music theory is just one perspective on what music actually means. So in thinking that "I've learned (a) music theory, therefore I understand music" is imposing an arbitrary limitation on your own perception of the universe. And that can potentially be harmful if you ever decide to decouple your mind from the cultural expectations instilled in you against your will from birth.
Music does not exist except for inside the brain. It's just vibrations that we have learned to interpret, through the lens of culture, and filtered by the physiological limitations of our sensory organs. So you can learn all about how people have historically made sense of these vibrations (i.e. music theory), but you are learning only what has been agreed upon by authority figures throughout history. You are learning what someone else decided music means. And by committing to music theory you are shaping your own interpretations of the vibrations of the universe in order to fit neatly with those expectations devised arbitrarily, albeit through empirical observation, by people whose culture is potentially radically different than your own.
I'll repeat, music does not exist except for inside your brain. Music theory can shape your perception of it, can help you make sense of what you're hearing, but does nothing to explain the why of music. And regarding music (or art in general) I would argue that the why is infinitely more important than the what or the how. And that must come from within you.
Also, self taught in this context does not mean the information just spontaneously appeared inside your head from nothing. You read it somewhere. So maybe you are interpreting the "teacher" part too literally.
Of course, if you're trying to get someone to pay you for your music, then yeah, probably play it safe.