One of the main complaints I've heard from kids in my area around 10 years and up is that banning them from the internet is essentially isolating them. Most families do not have home phones any longer, so their only way to communicate is often via online apps.
I think setting reasonable limits is important, but it may also be necessary to make sure children still have ways to socialize with other children regularly outside of school. Granted, I know nothing of how this works in China and maybe it's a non-issue there.