I'm pretty sure this used to be a thing a really long time ago, not sure why it got removed though.
If this is really the reason why we're going to add this, then why not add this to every pvp based game as this applies to them as well. There's not really a reason why this should be limited to skywars and survival games only (although I wouldn't recommend this for eggwars as people might start to kill-farm with alternative accounts since any player with an egg can basically get killed and respawn over over and over again to eternity).
Overall not a bad idea though, getting loads of wins by camping or waiting for most players to kill eachother every game before taking any action doesn't really sound fair either. It would be nice and fair for some really competitive players as well and so far, I don't really see why Cubecraft thinks this should be limited to survival games only, kills are just as important in many other games.
This has been suggested like a million times before already, the CCG Community really seems to agree on this so I don't see why this shouldn't be a thing. I do believe it might be a nice edition to Cubecraft.