I don't know if there are any games that see that much of a difference, only in Intel's favor. I haven't looked into it extensively, nor do I care about trying to defend Intel. However, I think some people are exaggerating the effect of the results that adding MS Flight Simulator will have.
LTT benchmarked the game and saw a 22% (at 1080p) advantage for the 5800X3D over the 12900KS.
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Add it to the 40 game benchmark from Techspot/HUB (who I believe said they didn't include the game because they couldn't get it running correctly on their Intel platform) and it doesn't change the overall average by a noticeable amount. This comped the 12900K to the 5800X3D, so it's not quite Intel's best, but I don't think it changes the overall results by much. Maybe it's 1% in Intel's favor, or even just flat even.
From their results it wouldn't even be the biggest outlier in the list. Doesn't really move the overall average either because they have too many titles for even one more game, even one heavily favoring one CPU by 20% to matter. MS Flight Simulator certainly is a strong outlier, even among other outliers, it's not as though there aren't games where Intel does better that on average it comes out in the wash.
The only way it matters is if you throw it into a six game benchmark in which case it can swing it by 4% (or more depending on what you compare it against) but a small sample size like that isn't as good because of that very reason. Unless you're going to contend there are a lot of games like MS Flight Simulator where AMD wins hard enough to make it an extreme outlier that are being excluded then your own argument can be used against you. Maybe there's some game out there that heavily favors Intel by that much, but I don't care to go looking for it. If it does exist, it may be just as or even more niche than Flight Simulator so I'm not eve sure you could make a compelling argument to include it as part of a benchmark suite other than to show the extremes that might exist at the other end.
My conclusion is still the same. MS Flight Simulator doesn't matter as much as people think if we're just considering averages. By all means get the 5800X3D if that's your game because it's hands down the best you can get. Otherwise adding it to a massive list of other benchmarks isn't going to move the average more than a fraction of a percentage point. Because it can't meaningfully change that average result the argument shifts to other factors and AMD kills it on cost, especially if you already have an AM4 board.