I'm thinking about dojo where the the teachers may be abusive, whether they are loud about it, or quiet and just hurt students when they can to prove they are "better" than the students. Teachers who ignore students that need instruction and play favorites. Teachers who expect to be treated like lords while they pour disgust on any student who can't handle what the teacher chooses to dish out. I've seen all too much of that.
I've also seen dojo where the students were not expected to be respectful to their fellow students, so there would be bullying and and brutality between students and groups of students.
The whole Cobra Kai thing is actually something I haven't run into, but these others, abusive teachers and abusive students, that I've seen far too often. I've
Even if you just look at traditional schools or any art in Japan, there is a gray line between "shugyo" and "stanford prison experiment."