How would the manufacturer know you were using a non-OEM part, though? As far as they're concerned their parts support so-and-so protocol, so they should be able to use it.
It's not a perfect analogy, but the rules on radio interference with devices spring to mind: you need to cope with some interference and you need to not emit it. This results in a more stable ecosystem, even though you could sensibly argue that if one side is stuck to absolutely, the need for the other wouldn't exist.