Obvious that if your hands are bone dry, adding a layer of chalk to them will make them slightly less grippy. However it's entirely irrelevant for me at least, as I never get bone dry hands with the temperature above zero.
As for the wet hands thing, well whatever happens in a lab, I don't give a fuck. The simple fact outdoors is, wet hands make me slip off things, dry hands don't. No amount of concocting excuses for trying to get a climbing-relevant degree work is going to change that.