This is an interesting discussion. I firmly believe that driving cars fast in general is an overall skill, while subsets of that skill are different types of vehicles. Some people can adapt to all car types and tire compounds, while others are better at only high-downforce slick-clad race cars or only "normal" street cars on sport tires (summer sport) and comfort tires (all seasons).
I am 50 years old now, and since racing games have gone online I have had periods that have led me to believe that I am better at one thing or another, only to have all that flipped on its head.
I was one of ten winners of what I believe was the first ever racing game eSports with Milestone's Superstars V8 (an Italian tin top series), which I believe was about the equivalent of a GT4 car at the time. No, I didn't get a trip to Monaco or anything. A copy of GT5 was my prize.
GT5 had the Nissan Academy and I got thoroughly humiliated in that time trial at the Indy infield with the 300Z (if I remember correctly). Therefore, road cars just aren't my thing, right? Aside from the fact that thousand of people put laps in the Nissan Academy vs. mere hundreds in the Milestone game.
I skipped GT6 because I could never get a connection with the servers from Argentina but played a lot of online DiRT Rally and Project CARS where I had wildly different results depending on the car/track combo, but in general I was better with the modern race/rally cars than with the road/classic cars. Therefore, road cars just aren't my thing, right?
Then GT Sport came, and you can see in my short video below that the vast majority of my 91 wins came in road cars. At this point I was thinking my reaction times at 40-something were now too low to handle high-downforce race cars. Therefore, I am a road car specialist, right?
Then I joined an ACC league on PC and I was pretty competitive with the GT3s, but still feeling that my age was affecting my ability to take a race car to the limit. Therefore, I am still a road car guy, right?
Enter GT7. I have done 40 Sport Mode races, with two Manufacturers wins (Gr.3) and one Nations win (Super Formula). I also raced for a year in an incredibly competitive league where my best results were in GR.3 and Super Formula while in the lower powered cars I was way off the pace. In the Super Formula season in that league I even took the championship to the last round and lost by only three points to an alien, beating another two A+ drivers in the process (I am only high A). Therefore, I am a high-downforce specialist, right?
Even in real life you have examples of F1 drivers failing in NASCAR, Indycar drivers failing in F1. Then you have GOATs like Loeb, Andretti, who can win in any car and any racing discipline.
In summary and taking into account that most of us are casual racers, fitting GT7 into our lives between work, family, activities, etc .. we are going to have peaks and troughs. A bad day at work can affect your racing. Racing is a lot about mindset. Maximum concentration is necessary. Beyond car/track combos there are myriad external things in our lives that can affect our racing.
Are some people better at finessing road cars? Yes. Are some people better at brute-forcing racing cars? Yes. Are some people able to better adapt to any car/track combo? Yes. However, I do believe that those who have the general racing skill set will be good at anything, while others may adapt better to race cars or road cars.
I will say I could never be a racer in real life. I rented a Ferrari GTB on a race track in Las Vegas a few years ago and while I was speeding past the grandstands at 200 km/hr seeing my wife and kids up there, feeling the visceral g-forces in the turns, hearing the tires squealing at the limit of grip, the deafening sound of the wind at high speed... I was aware death was a real possibility. And that held me back. Autocross and track days in my WRX do not give me that feeling of impending doom.
It's a mental game, and some of us just can't do certain things with certain cars, be it in a game or in real life.