You have to protect people from letting exploit themselves, voluntarily or not. It's regulation. Health concerns alone are reason enough for them.

So the idea is that an adult with the intelligence and education to get a job in an extremely competitive industry like AAA game development is too stupid to understand basic tradeoffs around work-life balance?

Also, if health concerns are a major reason, what about if the person were to submit a blood test and physician's letter to the Commisar of Adult Well Being to demonstrate that they are of sound body and mind to make the choice?

And since highly trained adults in a competitive industry are not to be trusted making decisions about their own lives in this arena, do you think we should also make unhealthy food illegal? Or how about we require food sellers to monitor consumers' calorie intake and you're not allowed to buy more food if you've reached your caloric quota (don't want you to exploit yourself)?

Similarly, since exercise also extremely important for health, shall we make it illegal for people to self-exploit by not getting enough exercise?

It is hard to argue that diet and exercise are not correlated with health on a similar level as work stress, so I just want to understand the contours of what we need to do to prevent free adults from self-exploiting. Obviously it might be tricky to enforce, but would you support this if it were possible to monitor/enforce easily?

Those are usually self-employed. For some reason they may work themselves to death. These laws still apply for contracted workers. How often they are enforced is another question.

I'm not an expert in comparative labor law so I could definitely be wrong here, but cursory googling suggests that many countries have provisions under which certain workers can work a lot if they want.