USB automatic discovery is meant for native Home Assistant core components like the ZHA integration:
ZHA integration support ConBee/RaspBee adapters nativly without the need to use deCONZ/Phoscon:
https://www.home-assistant.io/integrations/zha
https://www.home-assistant.io/integrations/zha#discovery-via-usb-or-zeroconf
I guess the idea is that most people who run deCONZ/Phoscon do so on a separate computer from the Home Assistant core instance and instead connect to deCONZ/Phoscon over the network via TCP/IP
https://www.home-assistant.io/integrations/deconz/
Just click the “IGNORE” button for the ZHA discovery and then search for deCONZ and setup yourself.