If parents don't want their kids on social media, get them a dumb phone, or use the parental control features. Maybe some parents don't care, and that's their prerogative. None of this is about protecting children, it's about "protecting" adults from "bad ideas".
The problem is many parents will not do that. Do those children then deserve to be taken advantage of by social media corporations?
Generally, things that are harmful and addictive such as alcohol, cigarettes and casinos require age verification. We dont just put the onus on parents because a child with bad or absent parents still deserves to be shielded from alcoholism at 12 years old.
So are gambling and cigarettes. As a society we've decided a reasonable compromise is that you can get the freedom to harm yourself at a certain age where you're assumed to understand that you're harming yourself.
So? Not all reactionary (if you mean "conservative") takes are bad. Sometimes they're better than the alternative: accepting bad parenting as some default and working around it with technological restrictions.
"Reactionary"'s origins as far are pure political DARVO and gaslighting anyway. It originated in the French revolution and basically declared "You are morally wrong for being horrified at my horrific and evil actions." That origin tainted the term for me personally.
The actual modern reactionary meaning of "referrant to a mythical past as a standard" always felt like it deserved a better term. But nobody would get what you were saying if you called them a "fairytaleland resident" or similar.