That would be really awful. The winner of the tiebreak would have a huge incentive to go for a draw. In chess, it's a lot easier to go for a win or draw than try for a win at the Grandmaster level. This would only increase the likelihood of there being more draw matches. I mean, just look at the 12 games in the WCC. Magnus was clearly playing super safe in order to draw the match and go to the tiebreaker, where he has a huge advantage. He did the same thing in 2016.