The LSU-Auburn rivalry flowered into full bloom, stinking of rotting flesh like the corpse flower, back in the early 00s before the Return of the Bama Dynasty. That was because the game was usually played early in the season between two teams in the top 25 and a loss would serve as a de facto elimination from the SEC race.
You beat Auburn, you didn’t just win one game in the SEC standings on a rival, you essentially gained two games on them because now you held the head-to-head tiebreaker. And good luck on that. If you were good enough to beat Auburn, you were good enough to not lose twice more in SEC play.