I like to win. Who doesn’t?
But I want to win because my team is better than my opponent’s, not because my opponent played without two players on a bye week and two more who were inactive because of injuries. It’s not fun to win by default.
Even worse is when it’s completely out of your control but directly affects you. For instance, let’s say you’re in the middle of a playoff chase and you need another rival team to lose. Unfortunately, that team’s opponent that week forgot to change his lineup, giving your rival a likely win, which prevents you from making the playoffs.
Make sure you have responsible owners in your league who will change their lineup every week, even when they are mathematically eliminated from the playoffs.