My wifes 318 is a "typical passenger car" <grin> and it gets almost un-drivable with over inflated tires. I think I could accurately paraphrase what you said and we'd be agreeing.
Hows this,
Within the design of the vehicles suspension air pressure has more effect on traction with tightly managed suspension and less on a more simplistic suspension with softer springs as related to the GVW of the vehicle.
Of course the speed you travel at and your driving envelope make a huge difference on results.
I think a lot of the stuff I do at the track is like those tests when you make stuff wear out faster by exceeding its duty cycle. a tire that's consistently over inflated by 2 lbs can last < 1/4 the expected life. Resulting in catastrophic failure of the case. On the street because heat is not as intense this is far less likely. But lose one front tire at 120 and for the rest of your life your torquing your lug bolts twice and checking the air pressure on your street cars constantly.... No matter what your technical voice says...
Dave