Wild guess is they have to reject palm input mostly because they make them too big. I don't even put my palm on my thinkpad trackpad so I don't even know if it has such functionnality as it isn't even needed.

Gesture is more an OS functionnality but I am not sure how a trackpad can be better or worse for scrolling or clicking. You slide 2 fingers, it scrolls right? you click (or rather tap these days), it clicks? right? Can a trackpad click "less" or even "scroll less"?

OK maybe some handle better wet fingers, that is maybe the weak point of my current trackpad.