Focus follows mouse was a thing in the X11 era too. We are still in the X11 era, and it is still a thing. (-: Until X11 window managers like IceWM vanish entirely, it will remain a thing.

* https://ice-wm.org/manual/#focus-models

I think of focus-follows-mouse as a different thing. FFM raises the window under the mouse, but doesn’t move the text insertion point (at least on X and Windows, the only two places I can remember using it). But the Apollo’s window manager was different - moving the mouse moved the insertion point along with it.