i mean... someone did try this with i2c. a couple of dead computer companies shipped a bus that i forget the name of, based on this concept. its descendant is the vga hdmi control channel spec (which was implemented as a de facto separate standard but is very similar)
ACCESS.bus by Philips (who developed I²C) and DEC, and the DEC variant SERIAL.bus (with different voltage levels) used by their keyboards and mice for a little while.
the name is escaping me