This solves some probelms, such as children accessing porn sites (oh the horror). But it doesn't solve other problems, such as predators accessing children's spaces. YouTube Kids is purportedly a safe, limited place for kids - and yet, there are numerous disturbing videos that get past the automated censors. Pedophiles stalk places like Roblox.

Your proposed architecture also achieves the goal of discouraging content-distributing entities from holding hard identification data, so it sounds good to me.