This is a danger to their mental development. Look at teacher forums all over. r/Teachers on reddit should be illuminating. Tech and parents sticking devices to their kids instead of raising them properly has resulted in utter disaster. If there was no harm imposed on children, I would agree that it is a nanny-state thing.
I myself grew up with a desktop computer from around age 7 and it shaped me early on in a positive way to be curious. Computers were also a central part of my social life. There are many positive things that kids can get out of computers, so I find the comparison with alcohol to be hyperbolic.
The usual figurative nanny state refers to a situation in which unreasonable rules and regulations are imposed on the behavior of grownups, not children.