If it doesn't already exist it will likely exist by a year from now. But don't get hung up on the example. The point is that having exception-based rules design with a thousand exceptions to choose from (feats) where within a party you can easily have dozens to remember makes the game more difficult to run.
The vast majority of those feats aren't going to do that, though, and most of them are exceptions on what the player can do, not what the GM has to remember.
A lot of abilities are this way. Maybe I'm thinking about charm abilities (which saves against are counted as one step better if you're higher level than the enemy).
I think you are thinking about how you get a +4 bonus to save against Charm if they attacked or acted hostile to you previously.
Or the flaming sphere that allows a basic save that means no damage on a success (and not merely on a critical success like every other basic save spell).
Edit: Huh, no, it's a regular basic, but it's in the spell description versus the stat block.