I never believe people who say that. My job is heavily child safeguarding and part of our role is to warn parents of the dangers of posting photos of their child online. We advise keeping profiles locked down to family members! There’s literally nothing beneficial to the child in posting their childhood photos/life online, the only people who benefit from it are the parents. When you say that to a lot of parents it seems to be a light bulb moment. I usually word it as, “how would you like it if someone kept taking photos of you and uploading them to lots of people who don’t know you?” Some adults really struggle to not see their children as an extension of themselves; Stacey Solomon is a very good example of poor parenting. She posts her children because it does something for HER, her children do not benefit from their memories and childhood being posted online for strangers to gawp at.
Edited to add: most parents get this when we discuss this, let’s remember that, most loving parents do not take advantage of their child to use for clout and free stuff. Thankfully, Stacey is the minority.