Seems like it would be easy to test. See how the AI does when revealed pieces stay revealed compared to a standard game.

It would effectively need to be a different AI to use that information. And what does it play? Humans? Other AI?

Also, given this is online competitive play likely that a significant portion of top human players are cheating and have aides to keep track of pieces.

That's a great point. It may even be condoned in some circles.