Hardware encoding cares about consistent real-time output above all else, with power usage as the runner-up. It can focus on that because software encoders are

Hardware encoding cares about consistent real-time output above all else, with power usage as the runner-up. It can focus on that because software encoders are just flat-out better for use cases involving quality - they have access to more flexible/accurate math, they don't necessarily have a real-time/low-latency constraint, they can be updated when new encoding tricks are discovered, they can be massively more complex without ballooning the cost of a device, etc. They're complementary options rather than competing. Each does something well, and it sounds like you want the thing that software encoding does.