Unfortunately, that is how people unprepared to do their jobs tend to deal with a situation beyond their control.
It's important to be strict with the students in order to maintain order in a classroom, otherwise it descends to chaos (trust me, I've been the studious kid in a class full of class clowns and a teacher that never commanded any respect), so it's not like I don't understand why she's doing thing the way she is.
On the other hand, she's doing more harm than good for, as you listed in the last page, not looking for evidence, talking to the person in question, getting physical, etc. The MC already mentioned how the teacher is a new graduate and doesn't have years of experience dealing with teenagers and cases of bullying, so it's clear they're pointing at the teacher's wrong methods.
If the story is well written, all of those points will be addressed in the following chapters and there will be ramifications for everyone involved. If that's the case, then the story isn't stupid, the story will calling out the stupidity.