Valid, but there's plenty of broken-down messes on the SNES and Genesis, too. I think his point was the percentage of terrible games is far less nowadays then it was 20 years ago, and I think that's true. When u go buy a modern game, for the most part, it's either really good, or just meh. The amount of video game abominations is a bit lower.
But really, I think it's cuz u went from bad Pac-man and DK ports on Atari, suddenly to games like Super Mario Bros, practically overnight, and so the standards for how to make a real good game weren't quite developed yet, probably, and it took some time to find what really works.