Everyone who has put at least a little bit of thought into UI design knew from the beginning that flat design is bad.
But no, it is 2019 and we still have scrollbars and buttons that are barely visible. Just because Google and Microsoft unreasonably decided to do it that way and every other one blindely copies that (because how can a those big, big companies be possibly wrong?). Fuck accessibility, even though we serve billions of customers on a daily basis.