The "right" amount of QA is about the cost of fixing errors. When you manufacture a ton of ROMs for a cartridge, there's not a lot of cost effective fixes you can do when an error is found. Hopefully it's minor, because if it's a major error, you're looking at a full replacement campaign and that's going to be super spendy.

On the other hand, how much does it cost to run an update on a Steam game? There's certainly a cost, and some of the cost is reputation, which is hard to earn back, but the tradeoff of being able to get patches is the reduction in quality control because problems can be patched.