Every elimination town has is a chance to kill imposters. In a 17 player game (assuming no doc saves, which, yes I am just going to assume that for simplicity), a no elim on day one is a lost chance to kill mafia, reducing, in a game that goes to f3, the number of possible chances to kill mafia from 7 to 6. We need to kill mafia with 4 of those. We do it two more times, goes down to five. Then mafia just needs to fool us twice, but going from 7 to 6 is still a big hit when you're basically just asking the investigative PRs to out tomorrow