> I cannot understand the love for matte display coatings...

Most folks cannot prevent every source of light from shining behind them. In my apartment, even sunlight leaking around curtains and indirectly illuminating the Landlord Standard White walls was image-damagingly bright on the handful of glossy-screened monitors I tried.

If you have total control over the lighting situation in your room, then, yeah, glossy screens can work... but most folks want to be able to use their computers and televisions in a wide variety of lighting conditions. [0]

> ...something oily/grainy looking.

I guess you've only seen bad AR coatings. The difference in image quality between the glossy screens I tried and the matte screens I have and have been continuing to use for the past great many years wasn't all that large... and the bonkers reflectivity of the glossy screens nuked what little difference there was.

[0] Most folks also don't like so much looking at their ugly mugs during dark portions of a program... glossy screens are -while not as bad as a mirror- so incredibly reflective.