Good question... I think this happens in real life too. I autocross quite regularly and was having a discussion the other week with someone about guys who only autocross their own car and do it for years on end. They are very quick in their own car, but then if they try something that's significantly different, they have to start from scratch.
I think most people can get pretty quick in LFS just by repetition, but I think the fastest guys definitely need some talent. One thing I don't like about hotlapping is that someone like me who is fairly quick but doesn't have any world records can get that one lucky lap that is not really representative of my speed. I feel being consistently quick in a race and being good at managing tires at the same time is more impressive than being quick on a hotlap. When I see someone lap within a few tenths of a world record lap consistently for a 20 lap race, then I'm impressed.
Then I guess there's also the question, are they one of those guys who can do this because they only race that one combo, and have done thousands of laps there....okay, maybe I'm really impressed when someone can hop in any car at any track and be consistently quick, that's got to show talent!