This could be an interesting new topic discussion,
but for now, all (3d) animation projects ive been involved inn, a matte, photorealistic or not, have been labled a matte.
Yes, that may be true, but that doesn’t mean it is a matte painting, simply, as you said, that’s the label it’s given; usually by art directors and HR people who stick everything environment related under the same banner because they don’t know any better.
Every animation company in the world seems to disagree with you. Please go tell Disney, Dreamworks, Bluesky, Pixar and every other 3d animation company that they should stop advertising for “Matte Painters”.
Don’t you think it’s the case that the title has become such a broads term used to describe a role that has far more expectations than a matte painter should be required to undertake? Another technique becomes available and they shove it under the matte painters role simply because its environment related.
Its possibly true that a matte painter as in the traditional sense simply doesn’t exist today, for one; painting is rarely used except to blend seams, simply because the alternative solutions are much quicker. Where photography doesn’t exist 3d will, and it will be the role of the “matte painter” to bring this to a photo realistic level and maybe re-project back onto the geometry. At this point you quickly fall into the category of environment artist, especially in smaller studios where you’re expected to add additional environment effects and in some cases comp the shot yourself.
To maintain the legacy of matte painting, especially given that its place is all put gone due to the evolving and every changing industry we have to hold a clear and distinct line between matte painting and traditional fine art/illustration landscapes etc. Matte painting is with intended purpose photorealistic, invisible and seamless with a live action plate. Another point been with the exception of establishing shots most DMPs shouldn’t draw attention to themselves or lead the viewer away from the focus of the scene. This is a skill in itself, to make your work look dull and unnoticeable:)
A matte painting ISN’T concepts, near photo realistic concepts, fine art, stylised illustrations, bird flapping in the wind, dragons, glowing mushrooms … i mean has anyone looked at mattepainting.org recently? i’m looking now and every image on the front page can be categorised as the above! there’s even one that looks like a water painting!!! dont get be wrong, great pieces of art in themselves … but not matte paintings!!
anyway before i start screaming like a random drunk person with fleas i’ll say no more 
Dave out.