I'm generally not a person to die on hills like this, but the disappearing scroll bars on macOS have really been a point of significant contention for me. Sometimes I just want to click and drag a scrollbar. And it seemingly takes an act of god to get it to appear (you can't just hover, you have to two-finger scroll first). And then in order to get it to stay, you need to keep your mouse horizontally positioned on th…
(Acrobat recently got this wrong, and I was hearted to discover there's a fairly active thread an the Adobe forums about how much of a fuckup this is. I am not alone! I added a comment or two, of course)