I mean, they /do/...eventually. Even figuratively and with the best possible survival course on the part of sentient beings, memories won't mean much when the very idea of figurative survival perishes along with everything else, unless people figure out how to avoid the heat death of the universe or whatever.
But Mercy makes incapacitated folks immediately get back up on the battlefield, which is impressive enough to warrant the catchphrase, I suppose. :o
