i Do a fair amount of tv mixing with music.
I agree that I don't think it's as relevant anymore, but I definitely try to make sure the key elements are projecting really well in mono:
kick, snare, hat, bass, lead vocal, and maybe one key gtr rythmn part.
I'm less concerned with some pads/synths, some bgvs, washy gtrs that may help give mixes width and depth in stereo.
mono reverbs/efx can help out a lot