Well that, but Elon is also downplaying the quality of the human vision system compared to the cameras Tesla's have.

They're just not that good - nowhere near human vision performance. And a human in a car has a surprisingly good view of the road and a very fast pan tilt system to look around.

Tesla's do not actually have 360 degree full binocular vision coverage - nor the ability for a camera to lean left or right to improve an ambiguous sensor picture.

So while I fully believe that vision only self driving could work, within the constraints of automobile platforms and particularly the Tesla and it's current camera deployments, it is not remotely similar enough to human visual fidelity for that to solve a valid argument.