How's hardware supposed to work without software?
Here's a similar situation with the macbook pro's speakers, from the Asahi Linux team (scroll down to "Audio Advances"): https://asahilinux.org/2022/11/november-2022-report/
Similarly they can't be used very effectively without special, complex software that involves physical simulation of the speaker hardware. Doing things this way allows them to reach an amazing level of compactness + volume, but at the cost of complexity
If Apple intended to support platform openness, they'd likely have made such software available to hackers. But they never enthusiastically encouraged that, so people like the Asahi team are left to reverse-engineer and reinvent everything they need that lives in software
With a hardware DSP? It's gonna have software in it, but doing this kind of processing in the upper most top level OS stack is certainly a choice.
It seems like a good choice. It’s computationally extremely light and you can update it much more easily with new features (they actually did this once - to let you change the beamforming mode in the menu bar)
It is also notoriously time sensitive however, and while likely the hardware can already ensure the synchronization between mics, processing in the OS itself necessarily means buffering for a significant period so you don't run the risk of draining the pipe in a non-realtime system.