One play is not what "cost us the game." It is a contributing factor in a series of plays that result in a loss. Your argument is only valid if you place an equal amount of blame on other players for a false start, holding penalty, roughing the kicker, a missed block, running the wrong route etc. That's why they say tou win as a team and you lose as a team.
Ok, what if, on balance, the 2 teams are pretty equal. Score is 10-7... they makes good plays and some mistakes, UT executes some good plays and makes mistakes, but on balance everything is roughly equal.
Then, on a specific play, everyone on the offense does his job and the team scores... except Pig needlessly blocks a defensive player in the back, the TD is called back and the team can't overcome that one bad mistake and ultimately loses.
I know it's a team game and I agree that it's difficult to place blame for a loss solely on one play over the course of a game. There are many plays, many opportunities to win a game throughout the entire game. But you gotta admit that without Pig's penalty that TD stands and UT wins that game. Just food for thought.