This line is indeed hard to define. I am not sure that such a limit would be enforceable even in China. However, it will have the side effect of making time gated games and other addicting dark patterns illegal or impractical, which it probably a net good thing.

To your last question, many jurisdictions are making fast food or sugary drinks illegal thus imposing a diet. I am fine with that. Some company are lowering health premium to those who do exercise, imposing exercise. I am fine with that too..