It can still be a lot more efficient to grab the scrollbar to jump to a section of a large document. For example, you can instantly get to say 3/4 of the way through by moving the scroll bar a very short distance, which when done with the scroll wheel or trackpad gestures could take a very long time.

The scroll bar is also sometimes a nice visual cue to the size of a document you've just opened for the first time, again something the wheel/gestures don't necessarily inform.

I have permanent scroll bars enabled in macOS too.

It is pretty much required if your primary interaction with the computer is through a drawing tablet. My Wacom has a touch-sensitive wheel on it but it's usually a lot more natural to just poke at the scroll bar with the stylus.

I loathe the modern trend towards hiding all scroll bars everywhere because of this.

Looking at this very page! Using the middle mouse button takes me 3 or 4 seconds to move somewhere close to the bottom of the page, much faster and less frustrating to grab and drag the scroll bar. Is there some easier method I'm missing?

Some old apps have a 'slow' scroll if you just roll the wheel. Moving around large documents in them is a zen koan, designed to break your brain.

Many graphics tablets don't have scroll on the pen.

Sometimes comfortable to drag with thumb trackball