I may be an outlier but, in general, I see reverb as a way to allow the vocal or instrument to bleed into the overall mix. Of course I want each track to stand on it's own but then have its edges lost in the mix. I realize I'm not articulating this well! And since I try to give my mixes a live feel I may be biased. Like a live jam in a good room I use reverb to let all the tracks settle in the mix and yet sound distinct when it's their turn. When I'm mixing I just can't separate myself from many years of great living room jams.