How old is your child? Younger than 6-8 it's easy to monitor what they're watching and enforce limits. By age 9-10 it isn't just about what they access in the home. Many schools in America are giving kids computer and tablet access, and kids are smart or curious enough to access social media there.
I agree that a big part of this is educating children about these hazards, but that also doesn't mean we should allow these companies to data science the shit out of our attention and will power. Many adults have concerning relationships with social media too -- exposure, pressure, and manipulation are key ingredients that are difficult for anyone to deal with.