i think they are dead because people are so toxic.
Back when this game first started there were always people in VC talking, but i noticed as time went on less and less people were ever in there and i really do think its because no one really wants to have to deal with someone when they are a toxic mess.
Its just safer for people to play and not be in vc at this point because as you can see from the comments there are people who feel like they cant enjoy the game with out ruining it for others which sucks.
now with blizzards monitoring chat system i feel people are less likely to talk because they dont want to lose their account, which i think could be another reason why people dont use VC anymore.