I can't really say that happened to me.
I mean, the first thing that pops in my head is if I play a neverending game, or at least one with hundreds and hundreds of hours. Sure, if that is the case, then I can't afford, time-wise, to play multiple games of that sort, so I better find the one that is best and devote myself to that. But that's not my style of play. Since I don't play MMOs or Gachas* or whatever, I've never abandoned one game because of comparing it to a better one.
And so if we limit it to my playstyle of playing lots of smaller single player games, well, this just doesn't come up, because I'd rather see the variation within a genre than compare two games at broad strokes and find one to be better. I mean, look at the OP'S example. Besides both being open world and racing, what do Forza and Mario Kart have in common? One's realistic, the other is wacky. One has items you can use, the other doesn't. To me, saying that one game does open world better than the other, and therefore one game replaces the other is just limiting. There are a lot more ways to judge a racing game than just that.
Or take a genre I know much better than racing that people above have chosen as examples: Metroidvanias. There's a huge variety of different aspects a game could focus on within this genre, whether it be movement and platforming, combat, exploration, progression systems, map structure, etc. I've played dozens upon dozens of Metroidvanias, and I still feel like I haven't exhausted the options of the genre. Do most of them compare favorably to my favorites? Perhaps not. But it would be crazy to say that SOTN or Metroid does everything that the other games do. There are so many stylistic differences between them that I would rather take the breadth than simply replaying the same game over and over. SOTN is not Super Metroid is not Metroid Dread is not Shantae is not Steamworld is not Prince of Persia is not Ender Magnolia is not Astalan is not Haiku the Robot, etc, etc, etc.
Now, one could then look at games that don't have much differences. I suppose there is some logic to that. If a game fails to provide any unique aspect and is totally derivative of another one, then there isn't much point in going back to it. But that's the key: going back to it. I'll still finish, say, Blossom Tales, even though it is a shallow imitation of A Link to the Past. I just won't play it again. And it's not JUST because I can compare it to a better game. It's because I wasn't impressed in the first place. I only replay the really good games regardless if I can compare it to something better or not. Thus, for example, I'll still replay Super Mario World even though I much prefer SMB3. Because they are both good, and thus both worth replaying.
So no, I can't relate. Sorry.
*OK, I guess in a way this did happen to me... I used to play Ingress while taking walks, now I play Pokemon Go. But that doesn't really count, since it's just something to have open while taking walks. But that's the closest example I can think of.
