In fact, the vast majority of teachers I encountered in life were exactly of that nature. To the point that studying turned into something disgusting to me that was associated with resentment and was done with the highest reluctance. A few exceptions here and there they were incapable of explaining the "why" of things, and the "how" only poorly, to the point that I was a student in my twenties before it actually occurred to me what the point of mathematics really is. I've learned to distrust the guidance of others and prefer to rely on written materials by the true masters of their craft, my own thoughts and online discussion.
I'll very happily spend hours learning obscure subjects and putting in the work as long as it's by choice and at my own pace. The moment there's homework, deadlines and tests I freeze up. The more drone-like people will do just fine under that sort of tutelage but anyone with a creative heart gets broken by it. You can't possibly imagine how many inquiring minds have been trashed by this "shut up and do as I say" mindset in teaching. Just typing this up now makes it painfully clear to me how many problems with attention I have that stem from this bullshit. Good thing I grew up shortly before it became the norm to stuff kids with amphetamines if they don't fit themselves to this perverted system, or I'd also be a zombie to boot.
Bah, I'm too disgusted to go on. Your pictures have soul and passion, anon. They're not copies relying on faults to give them character, like what hipsters produce, they're lovely experiments. Don't let that get taken from you by others' stupidity and shortsightedness. Tell your sis, don't let her spirit get crushed.