[StewardMcOy]

I see this framed as a touch vs. mouse debate often, and it's understandable since non-persistent scrollbars originated on smartphones, but I think even touch interfaces would benefit from persistent scrollbars.

At my work, we recently had a bug filed where a lot of users were reporting that one of the pages didn't have all the controls it ought to. It turned out that those users needed to scroll down to get to those controls, but they didn't realize they could scroll. At the common viewport size they were using, the page looked complete. It didn't look like there was anything to scroll.

If there was a persistent scrollbar, the user could have easily seen that there was more content to scroll to.

Now, you could say that the design of that page was bad if users had to scroll to important controls, and you might have a good case. In this case, the controls weren't the most important part of the page, and modern design favors decreasing density. There are always going to be cases where users aren't going to realize they can scroll.

Windows phone tried to solve this is in the most disorienting way possible by making sure things were always getting cut off on the sides that you could scroll, but other than that blip in history, there's been no standard replacement for the scrollbar for informing users they can scroll.