No it is not common at all. Driving a signal into a device that is not powered is hardly ever encountered.
A DVD player with digital output plugged into an amplifier
And no doubt consumer electronics is designed to be idiot proof.
If the two sub systems can be independently powered then a seriese resistor and catching diodes to each rail are a must.
How can a USB device be plugged in and not powered?
Is that considered ESD protection