It's one and the same, though.
A child will potentially have feelings about any images shared of them online in the future, and potential employers, or anyone else in their future lives, who may or may not have harmful intentions towards them, could find ways to access those images if they have ever been put online - even if you think they are locked down.
Do you think that the image of your child on meta can't be linked with details about his name, date of birth and school, just because you haven't personally published them all in the same place? There are ways of making these connections. You don't need to spell it out for them.
If there is an image of your child on meta, and an image of your child on his school website, then those two images can be matched via facial recognition, and it is then very easy find out who your child is and what school he is at, and from there, where he lives. They already know you are his parent and your full name, from your profile. They can then match images of you from facebook with you elsewhere on the web. It becomes very easy to build a picture of your entire lives from what you think is limited information. And that information is there forever, so people in his future life will be able to access all of this historically.
Of course you could say "why would they?" - but I'd say why would you give them the chance when you don't need to? You don't know what could happen in the future or what might be going on in your children's lives, or who might be interested in them, for whatever reason.
Meta have already demonstrated how little regard they have for people's rights of ownership over their images, having recently decided to feed everything public into AI training unless people opt out, despite the fact that they don't own any intellectual rights to those images. What they are doing should be illegal and it's only a stones throw away from them grabbing your private photos as well.
People are sorely lacking in awareness around these things.
I just don't know why anyone would take the risk.