That’s more to give control to designers, they can have an icon that looks very subtly different in the small settings app size verses the large App Store size or to provide more detail in a retina icon. In theory, it also allows you to use techniques such as app slicing to only deliver the required assets to a particular device.
As for business icons here, there seems to be little wrong with most of the images as they are delivered via. the API as far as I can tell. It’s something in the client app that’s optimising for sharpness of straight lines and isn’t being HiDPI aware (I can see clear signs of pixel doubling for example).