Parents used to offload parenting to streets, fields and forests for decades. I don't think the offloading is the cause. But switching the offloading provider to SOCIAL MEDIA (of which Youtube is one) might've been.
Yes but streets , fields and forests are more interactive than YouTube. It makes your brain work and work out solutions to hard problems. Youtube is just passive
The modern trend is parents spending a lot more time and involvement with their kids then used to be the norm. The norm was that kid were outside unsupervised doing whatever. The expectation on parents went up rather then down.