I think that saying it should be "difficult to drive a car fast" is as questionable and over-simplified as saying that it should be "difficult to be realistic". Both statements require further clarification, and both are potentially valid.
If you are at/over the limit, it doesn't matter whether you got there from bad driving or expert driving. If the sim is forgiving, both good and bad drivers will benefit. The bad driver who finds the limit by misjudging every corner will crash less/get away with things more often, and the good driver pushing for a record lap time by balancing the car at the limit at all times will more comfortably 'explore' this region of grip/save the car when pushing too hard.
When I describe a sim's difficulty, I'm considering its behaviour at and over the limit. I'm already assuming that all cars are easy to drive below this limit. So with AC, which I think feels too easy at times, I'm not referring to the below-the-limit behaviour that is bound to be easy. Therefore I don't accept the popular response of 'they're supposed to be easy'. I'm saying it seems too easy at the times when I expect it to be more difficult. At some point any car is going to be difficult to drive no matter how forgiving it seems. Every car has limits - you can lose control of each one in AC by exceeding them. People like to say of AC 'if you're finding it too easy, you aren't pushing hard enough'. I struggle with this idea for the same reasons - it seems like stating the obvious. Everything is going to be easy and then become difficult at some point.
All sims can be described like this, and reality too - it starts easy, becomes difficult, and then you crash. It's how each sim transitions between these states that varies. For example, AC appears to have a window between easy and difficult that feels wider than that of iRacing. You can push the cars beyond the limit in both, and when you do, they are both difficult, that is a given. But I find this wider window of driveability in AC to be questionable at times, and it's not because I'm still below the limit. This window is happening when the car is moving around underneath me in a way that suggests plenty of tyre slip. I am getting interesting combinations of understeer and oversteer. I am steering the car with the pedals. I am at the limit and it feels like I'm getting away with too much at times. In the same manner, in iRacing, I can be getting similar sensations of slip, balancing the car with the pedals and all that fun stuff at the limit, and it'll let go
sooner than expected and it feels like I
should have been able to get away with more.
Which is more accurate remains up for debate - I think both are very accurate in some areas, but both have problems, with AC being too forgiving at times, and iRacing being too unforgiving at times. (However, iRacing can also be too easy at times, particularly with the current build where there seems to be too much grip across the board, whereas I've never thought AC is too difficult... so that could mean AC feels right to me a bit more of the time.)
These elderly businessmen who are finding GT3 cars easy to drive are likely making good use of traction control. TC is very effective on sticky cars like this - they're even easy in iRacing with TC on. But switch it off and they are snappy beasts, whereas AC's GT3 cars seem rather easy to drive at the limit even without TC. You can practically drift them, as the tyre is so forgiving.
As for the Skippy, they're very different in rF2 and iRacing, so at least one of them has to be wrong. The one in rF2 seems to have much less grip, is more sensitive to lift-off oversteer and behaves a lot more like the Skip in iRacing from a few seasons ago on NTMv4 (the one that many said was too hard). However, it's easier to drive than this NTMv4 Skip, as it loses grip so progressively at slip angles that would be unsavable in iRacing. The one in iRacing now has, imo, way too much grip, yet when you get it sideways it is still somehow harder to drive than the one in rF2, as iRacing's over-the-limit behaviour is still the most unforgiving.
So for me, the Skip in rF2 is the one that feels most correct - it's the best of both worlds - it has the slippery feeling of my favourite iRacing Skip from NTMv4, but isn't as scary due to the beautiful progressive feel once you are sliding. iRacing's Skip has so much more grip in comparison, and therefore seems too easy in general now, but it's still too difficult to manage beyond certain slip angles.
That was much longer than planned! A cookie for anyone who read all that. Difficult to describe these sensations in a few words