I think you're clearly missing that industry benefits from getting children hooked on games, be it free to play games on a console or phone which might be tied to a parent's credit card. More traditional, not free to play, games also have the same effect, buy the game and keep buying expansion packs or the next iteration of the game.
If the kid is old enough, in their teens, they might drain their bank account which was to be used as a college tuition/cost of living fund.
We regulate gambling for good reason. Some of these games, with loot boxes and leveling, manipulate people using known psychologic techniques to make them get that dopamine hit by getting little rewards.
You're missing how industry practices can become manipulative and abusive because they are chasing short term profit for themselves and not long term societal benefits. Regulations come into play to ensure that our society does not suffer due to excessive greed/profit creating manipulative or abusive situations for consumers.
Just because China seems to be willing to regulate to the benefit of their overall society this time in a way that isn't harmful to people's rights (only minors and limited penalty), does not make up for their horrible human rights record and their ongoing abuses.
I say this as an American who was probably a bit too hooked on a few video games as a kid, playing 6-7 hours after school most days on one game in particular through highschool.
An automatic opt in for minors, with an optional ability for parents to opt out their kids, seems like a slightly better way to go if you want parents to have more control over this policy. Behavioral economics says you should allow people to opt out, but by default they should have the policy applied because it takes time and effort to opt in (e.g. opt in vs opt out in policies for organ donation in countries around the world, opt out policy leads to much higher organ donation rates)
What is most highly problematic about this policy is that this system is using the Chinese system of having to identify yourself online and their continued monitoring of you and all your activities, grading them and judging you. It is huge human rights issue in regards to ability to make your thoughts known - political or otherwise. If they implemented it in a way that doesn't use that Chinese social credit system, then I wouldn't have any issue with it.