Ask HN: Why was Usb Audio Support Removed in Android 9?

Since Android Pie/9 the support for AOAv2 which enables using usb audio devices we removed from Android (see https://source.android.com/compatibility/10/android-10-cdd).

Why is it that highly useful features like this are removed without any explanation, workaround or alternative solutions?

On iOs you can use external sound cards for music production or using your car stereo if it does not support Bluetooth.

Anybody on a relevant Google team care to comment? Thanks!