It's not stupid. The fans were right about Danny White, just like they were right about Romo. Those dudes could not get it done, and it was obvious.
If the goal is to win a SB then you are going to need a guy who can get it done, or pray that you win lottery one season with a buss driver.
Danny White had nothing to do with that '81 team's Achilles heel, which was stopping the run. That defense masked that problem via getting a lot of takeaways. That drive that SF had resulting in the so-called "catch" was a drive where they had run it down the Cowboy D's throat to get close to the goal, and then Montana and Clark were able to make that play. But none of this had anything to do with Danny White. He did not play on defense. Then, on the following drive, he hit Drew Pearson over the middle, and he would have scored if Eric Wright hadn't made an excellent tackle. They were 10 yards from field goal range, and had the best kicker in the league. Then, on the next play, White was hit as he threw an incomplete pass. Unfortunately, the boneheaded refs incorrectly rule that incomplete pass a fumble, and that sealed SF's win. The refs also missed a blatant pass interference on Doug Cosbie in the endzone on third down that prevented a TD. We settled for a field goal, thus being robbed 4 points because it should have been a fresh set of downs on the 1.
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So, yes, blaming that loss on Danny White is ridiculous. He was robbed. The defense gave up the winning score, not White.