At least in the context of this article (iOS app bloat) this is no longer the case - developers upload all assets for all pixel densities, but Apple repackages for each specific device, so that each device only gets one set of assets. Same goes for binaries for multiple architectures - each device only gets the binary for its specific CPU architecture.

Also to the GP's point - Apple also now no longer supports splash screen images, so that element of bloat is no longer a factor (though some legacy apps have retained them pointlessly).

I think for non-game apps assets are not the primary driver of bloat.