Chances are no one fully qualified in P-51 attempted to turn fight in it at 150kts.
Pull any significant Gs at less than 250kts good luck keeping both wings flying.
True, no doubt.
But it can be compared to how it responds to an FM. Does the 51 feel like it did when I flew it, at least getting the basics “right”.
Back in the day Earl, a WWII pilot and test pilot, who tested several planes, but mostly flew the P-47s, P-40s and I think the P-38, could at least tell use if we’re in the ballpark on the feel of it. Every plane flies different, yet same FM. Is not an exact science, but it can help at times.
Its just an add-in subject. I don’t think anyone sees it as some breakthrough.
One can go to things like Fighter Pilot USA and fly a plane in a dogfight situation to get the feel of real flight.
I just think there are a lot of pros and cons comparing FMs by those who never did it. Opinions snd misconceptions abound. I think a player just either likes it or they don’t. Some also confuse FM with Damage Model. <shrug>