We’ve heard the same thing about knuckleballs.
They have a tough time reading it because the “dot” you look for on a slider is on the bottom. I think it’s pretty neat myself. BUT….
I’m glad I don’t have to try to hit it. 😀
I played men's senior league baseball for a few years and we had a several X major leaguers on our team or in the league and at their age most had learned to throw a devastating knuckle ball ( speed was long gone ) that left even the best hitters beyond frustrated. If a guy was on that day you swung wear the ball wasn't and prayed.