Another minor reason is that AFAIK ZHA has to run on the same machine as Home Assistant, while Z2M can run on a different machine, and is less resource intensiv

Another minor reason is that AFAIK ZHA has to run on the same machine as Home Assistant, while Z2M can run on a different machine, and is less resource intensive than all of HA. So you can plug the zigbee coordinator usb dongle into a centrally located OpenWRT router and run Z2M on it, while your Home Assistant machine can be located anywhere that is convenient.