This is a pet peeve of mine too and I agree with all your points. But I think more often than not, such custom scrolling may happen as a result of trying to con

This is a pet peeve of mine too and I agree with all your points. But I think more often than not, such custom scrolling may happen as a result of trying to control something else, like some infinite scroll with virtualization that would normally start shifting elements and make the scrollbar behave funny. not defending this pattern, I just don't think people fuck with the scrollbar just to make it "better". they probably try to make it as close to original as they can which of will of course be, nothing like the original :)