No, I've certainly seen a lot of education sector academics argue for allowing them. Just do an internet search for it and you'll find "experts" on both sides. I don't know about the teachers at the coalface, I can imagine their word carries about as much weight as any pleb worker in a bloated bureaucracy like education. I have seen stories about teachers being assaulted bullied and attacked by child and parent when trying to enforce these bans though, so I would be surprised if even those are unanimous on the issue.