why are some teachers so insistantly aggressive about punishing children for having interests they dont understand?

I remember this shit happening while I was still in school too where anything that was really popular among young boys was instantly labelled a distraction that you could be punished for. pokemon, yu-gi-oh, beyblades, all of them were banned very quickly from my school and I remember on numerous occassions teachers calling them stupid and pointless and going on tangents about how they dont let their children engage in interests like that because it rots your brain. what was the deal? And the main excuse would always be that it was a distraction. Like yeah thats the point pricipal dr.deepshit, children cant be expected to be 100% focussed on their schoolwork for 8 hours a day. they need to have outlets to blow off steam because school is fucking hard. let kids like things you stank asses.