The biggest differentiator between a studio that creates a really high-quality [product] and a studio that doesn't isn't the quality of the team.
It's their dev tools.
If you can take fifty shots on goal, and you're a pretty shitty hockey player, and I can only take three shots on goal and I'm Wayne Gretzky, you're probably going to do better.
That's what tool are. It's how fast can you iterate, how stable are they, how robust are they, how easy it is as a nontechnical artist to move a thing.