So why take a Mercy, when a Lucio would do almost the same - speed-boost the team from spawn?
How about instead - they don’t all rez where they are, they rez where Mercy is? She gets herself into the center of them, and they rez around her in a tight clump? Now don’t tell me there’s no counter-play to that. It’s called “ult-economy” - i.e. don’t just “wow, we just comboed every ult in the game” (Jeff talking about how “un-fun” Mass-rez was for the enemy team), save one or two. Unfortunately, that is something that most people apparently couldn’t do which is why we’re in this mess we’re in.