Who are the most surprising Super Bowl losers who never returned?

With the Patriots defeat, it looks like they’ll have a solid chance to return. Young team with a good core and a great coach. It got me thinking about teams that surprisingly never made it back. Three come to mind:

1984 Dolphins: I might be biased as a Dolphins fan, but looking at it objectively, I don’t think so. Top 3 coach in the NFL, best QB in the nfl (or second behind Montana) and the best receiver duo in the NFL. They went 14-2 and cruised to the Super Bowl. I don’t think any Dolphins fan would be able to process that being the last Super Bowl they’d make for 40 years after being a common team in Super Bowls over the previous 15 years.

2012 49ers: Im referring to the core with Harbaugh in specific. I don’t think anyone was surprised that Kaep didn’t return due to his play style putting him at injury risk, but I dont think anyone foresaw Harbaugh being pushed out and the team needing a whole rebuild before competing again

2021 Bengals: This one is slightly more believable due to Burrow’s injury history and the existence of Patrick Mahomes, but this team’s competitive window was a lot smaller than I had assumed.