China has forbidden under-18s from playing games for more than three hours/week

I similarly have mixed feelings as well, but for slightly different reasons. I've read about studies that say that musical training (which is often believed to translate to improvements in other cognitive aspects of life) doesn't actually correlate to said improvements, and I suspect that the same might be true for games (e.g. solving game puzzles doesn't necessarily mean you get better at school math or whatever)

This line of reasoning is also supported by research on correlation between games and violence (i.e. the consensus is that no such causation relationship exists).

All of these suggest (to me) that gaming is just its own activity without much impact on life other than opportunity cost itself.

However, there are some aspects of gaming that can affect overall well-being, specifically aspects related to repetitiveness (e.g. grinding). Repetitiveness is something that does come up in a lot of disciplines (e.g. its soothing effect in autist kids, or repetitiveness as tool in the context of meditation, etc).

The "addictive" aspect isn't necessarily a bad thing either, IMHO. Games are, almost by definition, supposed to be engaging. But that addictiveness may come in a form of trade-offs, for example, back in the day of grindy RPGs, delayed gratification was basically the entire point of grinding. The one aspect that I think is justly vilified is monetization strategies that tie to addictive elements of gameplay (especially the gacha variety) and this is something that I'd actually commend China for trying to address via regulation.

You want them to learn social skills (for future reproductive success), study math/science, etc.

The US brain-drained the entire world for more 100 years, and the CCP likely sees efforts like this as a way to catch up.

I disagree -- I think you become as powerful as the US by being the best place for smart people to move to, not by forcing your populous into a predetermined mold -- but they're never going to be the attractive bastion of freedom that the US was perceived as.

But I would caution against being too picky about single-player experiences. The most meaningful games for me were not generally story-based, they were "play-based". Exploring mechanics, exploring a world, seeing what might be possible, what might lie out there to be found. Zelda, Pokémon, etc. A game doesn't have to be a work of literature to be meaningful and worthwhile; children in particular benefit from play. I would cite Minecraft as a good modern example of this ethos (which can of course be played either alone or with others, and is valuable in both modes).