The article asks a very general/philosophical question, but then goes on to say the FD is not really that special because we can find other sets of orthogonal b

The article asks a very general/philosophical question, but then goes on to say the FD is not really that special because we can find other sets of orthogonal bases and transforms between them. I would argue that despite this fact the frequency domain and by extension the FT is special compared to many other transforms, because we can actually observe them in nature. Two examples: a lens will perform a 2D FT of an input image on a collimated beam, we can observe this with e.g. a screen. Second example, we can measure the wavelength (or frequency) of light by projecting the output of a grating or prism onto a ccd again a direct measurement of the FD (similar measurement can be done for RF waves).