Not just Firefox, all programs in Windows 10 allow shift+click to jump. The only exceptions are new UWP style scrollbars (the ones that are affected by the "Automatically hide scrollbars in Windows" setting). Fortunately I don't use any of those, other than start menu and settings. Interestingly (as mentioned in the article) EdgeHTML based Edge is not one of them, scrollbar is always visible regardless, and shift+click works.