And yet, several mobile apps I use routinely have found a way to make it work reasonably well. They use a slim line of a scrollbar to indicate where you are, and if you touch the scrollbar then a larger finger-friendly handle appears which can be used like a traditional scrollbar.
But I'm much more forgiving of UI compromises that are forced by the limitations of mobile devices. It's when those same compromises are used on the desktop that I have a problem -- that's just degrading the UX for no good reason.
I agree it's sloppy on desktops, but it helps to understand the reasons why the sloppyness happens. Kind of like electron apps :p
Touch scroll bars don't need to be precise because most of the time we can just scroll normally. But it's nice to have an ability to jump to a specific part of the document in a consistent way.
This, unfortunately, describes half the features of iOS. Apple is deeply in love with the undiscoverable UI - and then NOT DOCUMENTING it.
Drives me absolutely crazy.
That said, I stumbled across it by accident first.
Scroll bars only work with precision mice actions, and now desktop UX is legacy UX, mobile UX concepts enroach onto desktop UX, because developers do not like to create special cases, because that is more work and thus more $$$.