Why do people feel compelled to mention whether or not an umpire's call hurt their DD's team?
Because sometimes people's emotions about the situation get in the way of their ability to stay objective about a situation or listen to other people's opinions. You have mentioned yourself that you have been blamed for the outcome of games. That's emotion getting in the way. Clarifying that this issue wasn't a game-changing situation is basically a statement that the OP is trying to look at the situation objectively.