FWIW, I can do the same time in the 650s and 488, so I'm not sure it's true
The main thing is you need a driving style that's compliant enough to allow you to get the right angles in T1 and T2, it's mostly just coincidental that the 650s already helps with that with default setup.
The 488 especially is more than capable of doing the same kind of lap times I've been posting on the practice server. I'd be surprised if the R8 can't also be brought up to that standard since it has the correct tendencies for this kind of track.
People put too much stock into what cars the faster guys are racing in. Sure, some cars suit some tracks more, but you'll get a lot more in the long run if you stick with one car until you've learned it inside and out
I raced the 650s for 2 years until I even thought about starting to learn the 488.