But it will look disconnected from every other app on the user's system. Whatever style the user currently has installed on their system, if the scrollbars on

But it will look disconnected from every other app on the user's system. Whatever style the user currently has installed on their system, if the scrollbars on your app look the same as all the other scrollbars they ever use, they'll recognise them instantly and know how to use them instantly, with zero additional cognitive load. You users might be using enough of their brain to figure out your app (maybe because they're also being partially distracted by their boss/child/phone/pet/music) already, don't make them spend time thinking about your gorram scrollbar as well.