The power adapter that comes with the Switch supports only parts of the usb-pd standard. That’s why it didn’t work with your other phone. You’re absolutely rig

The power adapter that comes with the Switch supports only parts of the usb-pd standard. That’s why it didn’t work with your other phone. You’re absolutely right about the protocol being unreasonable with two batteries connected together. FireWire has the same problem. You could charge a FireWire iPod from its wall adapter, and you could charge one from an iBook. If you accidentally plugged the AC adapter into the FireWire port of the iBook it would destroy the port. Buses where every participant is an equal peer are expensive and complicated.