I just looked at amazon customer reviews on this thing (goes back to 2008), and one guy was warning about this HDMI issue in 2011, still giving it 3 stars. I can't remember my d class Panasonic receiver model (ex has it), but it's of a similar vintage and didn't have this "feature".
But you're right, it just seems like HDMI has been around forever, but it wasn't really the standard it is until recently.