Even before trackpads were good enough, scroll wheels were a thing (and I still prefer them). Your dismissive "mostly a progress indicator" is burying the lede

Even before trackpads were good enough, scroll wheels were a thing (and I still prefer them). Your dismissive "mostly a progress indicator" is burying the lede: yes, I've seen scrollbars as primarily progress indicators for more than a decade now, and I'm still irritated when they're not there! (They're also useful to quick-jump to a specific portion of a page or to scan very quickly without swiping a million times, but those aren't as important as their progress-indicator function most of the time.)