I think it's just for the purpose of having two (or more) final results for the different categories. F1 vs GTO there's no doubt on who's gonna win, but if you think for example to the classic 24h, different categories are running at the same time and the competition it's just amazing!But where's the fun part to do that? If you add diferent classes racing the same round it will be just like F1 with the 2 Mercedes...
Your "classic 24h" example is right, ok... but there isn't enough content at the moment to do that I believe...I think it's just for the purpose of having two (or more) final results for the different categories. F1 vs GTO there's no doubt on who's gonna win, but if you think for example to the classic 24h, different categories are running at the same time and the competition it's just amazing!