Regarding real-world use of WebP - what makes it much worse, in my experience, is that so many web servers are set up to do a lossy conversion to WebP from the original file, most often JPEG (to cut down on bandwidth, or just to satisfy a web speed report originating from Google and therefore pushing Google's technologies). The difference is often very noticeable, e.g. textures smoothed out of existence. Helps to remove WebP from the Accepts header to force servers to serve the original.

It means the technical differences between format, and the real-world choice of which file you want, don't match.