First, let’s get clear. All organizations are complex. So if you’re doing software dev you are in a complex system. Aspects of it also have the possibility for chaotic events (such as the Martian Lander disaster).
But let’s consider something necessary to consider in even simple situations. Take two minutes to watch Lucy in the Chocolate Factory.
This is a simple situation. Too much work causes problems. Managing work levels is something necessary to do the job.
Is it sufficient to get quality? Maybe in this situation. But if you take the idea of managing WIP into a complex situation, it’s still necessary but no longer sufficient. The point is, while complexity tells us we can’t see everything, it doesn’t mean that there aren’t necessary things to see.