My feelings are it's only one stop & I know some will go on about how they need [LIke] bokeh or DoF or something, that's fine and if you only want that, well f/1.2 or 0.95 on a full frame is where you'll probably end, needing 1/8000.
These days I think most new cameras have a good electronic shutter, I know my Fuji goes up to 1/32,000.
So for a lot of situations the 1/8000 mechanical shutter is a moot point as you can just move into the E shutter. And yes I know the rolling shutter effect on moving subjects.
Here's one at ISO200 [native base on the Fuji] shot at 1/20,000 at F/1.2. Could have shot this as 3.2 I guess if I only had 1/4000, wouldn't have made much difference but it's just an example
It's extra helpful when it comes to smaller sensored cameras. I shoot with an M43 camera so my depth of field is always doubled from the aperture. If I want to shoot a photo with the depth of field of a f2 lens, I need to be shooting at f1. F2 is perfectly doable at 1/8000 from my experience, but shooting at f1 demands a much higher shutter speed. My E-M1 has a max (electronic) shutter speed of 1/16000 and there's been times where even that wasn't dark enough.