I agree with you, without a trackpad scroll-bars are required. But in workstations screens are often huge and I guess that it's possible to have a readable/comfortable display of the whole page at a 100% zoom. I have not a workstation, I use to work comfortably on a laptop (MacBook Pro or MacBook Air), a tablet (iPad Pro) in a degraded mode when I am lazily lying in bed in the middle of the night, and a smartphone, at a café, where editing is boring but reading is still rather comfortable using double-clicks to zoom in and out. So I can begin a page here and editing it anywhere else. It's funny.