Agreed.

More problematic is when IT is classed with SS, for example. I remember qualifying pretty well at the Glen in my lowly RX-7 once. I had a shot (ok, a longshot, LOL) at a trophy, actually. Welll, not so fast. My lap times were better, but a SS car got by me after the start down the long back straight. It took me many laps of nearly rubbing his bumper everywhere EXCEPT the straights until I could get by, and by then the leaders in my class were long gone.

He was winning SS, and had negative interest (blocking) in letting me by.

So keeping cars that have similar characteristics (as much as possible) together, but at significantly different speeds, makes sense. (ITS and ITB for example), where possible.