Back in the day, Netscape Navigator had a "Reload" command in the View menu, advertising the shortcut Ctrl+R (or ⌘R on Macs). When Internet Explorer came out, they followed IBM's Common User Access interface standards, so their View menu had a "Refresh" command with the shortcut F5, although secretly they did handle Ctrl+R too, to make it easier for Netscape users to switch. Likewise, when Firefox was pushing to take over IE's marketshare, they added support for F5 even though they still advertised Ctrl+R as the Reload shortcut.

Today, in Firefox Nightly, the View menu does not have a reload command at all, never mind a shortcut. Nor is there a mention of it anywhere in the hamburger menu that I can see. Ctrl+R *is* mentioned in the tooltip of the reload button, though I wonder how many people would actually check that.

I guess we've shifted from the era of "computers need self-describing interfaces so people can learn how to use them", to the era of "there is ambient, pop-culture expectations for how computers should behave, you just need to follow them, not try to explain them".