Re adoption. I don't know what country you are from, but surely there must be situations where children are removed by the authorities because they have been abused or there are issues with substance abuse for example?
Yes, that's a fostering or temporary care situation. If the parents still want their children (which most people do, bad parents are not usually bad people, just people making bad choices or struggling) then social services work with them long-term to the point where their children can be safely returned to them. In extreme cases, the children may be placed with extended family or friends. It never happens that children are taken from parents who still want them and given permanently to strangers without the parents' consent. If I were in your country, obviously I wouldn't post photos of adopted children.
imagine what it will be like for this generation when they apply for a job and have 20 years of pictures from their entire life online published by their parents, their parents' friends, aunts, uncles, grandparents, etc.
What if my son becomes prime minister (heaven forbid)? He may not want journos going through pictures of him in a nappy with yoghurt in his hair!
As an employer, I will have a look at potential employees' current social media accounts to see if they have posted anything alarming in recent history. I have no time or interest in trawling through their friends or parents' friends (?!) social media accounts from the last 20 years to see if I can find something vaguely incriminating.
I also doubt that journos are going to bother going back through 30-40 years of someone's mum's social media posts to see if they can find a nappy-and-yoghurt shot of a future prime-minister, but if you really believe that's possible, you could just lock down your social media account.
I'm obviously not saying that people HAVE to post photos of their children. If you want to let your kids decide, fine. I just think the "What if" scenarios that are usually put forward to shame parents who do post SM photos of their kids are wildly improbable.