[low_tech_love]

Sure, publishing is one thing, but not even taking the pictures and/or allowing parents to take them is the problem. It is lazy blame-avoidance backed by some kind of hysteria (if you ask me). Of course they need some consent form if they’re going to post it publicly, but the parent group should not be considered “public” in my opinion.

[aiilns]

Thinking of myself as a parent I'd be quite angry if photos of my children ended up on Instagram (private profiles or not) or any company's servers.

So in your place, knowing how brazen everyone is with privacy I'd actually be ok with this measure. It's not like you can't take photos/videos of your children and their friends (with their parents' consent) outside of school & during your time together.

Some 200 years ago photography hadn't even be invented, and only the last ~50 years has it been mainstream. Not every moment has to be recorded, relax, have fun and take a few photos so you can reminisce when older.