I'll only respond to this but I do see a lot of people share your viewpoint. I think I agree with you partially. There are ways to rot the brain on YouTube. I noticed it maybe 8-9 years ago for me. I unsubscribed from all the gaming channels and only watched tech/EE/CS videos. It got to the point where in college I had weeks of 40+ hours of YouTube (does it adjust for 2x speed? Unsure) but it was mostly on STEM content. I believe that's what let me ace my classes in my later years. I just learned better from them than reading textbooks.

So, please don't give up on trying to only block the brainrot. Also, kids are crafty and usually have more time than adults so be prepared to fight an uphill battle once they figure out VPNs, DNS, and other ways.