It's s statement of fact, and a trait I encounter all the time. From you, and from plenty of other fans. You can't stand to see them look bad or be criticized and feel a compulsion to rush to the rescue and justify every move they do or do not make.
"must have" was never said, missed opportunity was, especially based on what this team has, and what it's paying for lesser play. And what other teams do doesn't justify the Cowboys making a mistake.
Nobody is saying "all", don't create a Strawman trying to argue something nobody asked for to again justify this blunder.