You’re right that it isn’t a causal relationship, yeah. Though there are two ways you could interpret my argument:
1) If teachers were supposedly so good at indoctrination, you’d think they’d be able to get students to behave
2) If students aren’t willing to give teachers basic respect, then why would they listen to teachers lecturing about their “ideologies”?
I’m not saying the education system doesn’t have issues, because it definitely does. It’s just that people are blaming an imaginary problem