Moss shouldn't spread to deepslate

So this guy called pixlriffs on YouTube made a new mining technique where you basically spread moss onto stone and instamine it with an axe. He managed to do this all the way down to bedrock. This would remove the challenge of deepslate levels with deepslate not being instamineable, so I think moss should spread to deepslate at all. It kinda makes sense too because deepslate is different from normal stone and harder to mine