It's far more complicated than this now, but rear aerodynamic devices first appeared on GT cars because if you take a road car up to 170mph or whatever pretty much the highest priority issue you're immediately going to run into is rear aerodynamic stability. Modern supercars have this sorted (often with wings themselves) but traditionally a road car is going to generate rear lift which is not a good time at racing speeds.
Front lift is also a consideration of course, and say the 911 got a front spoiler before a rear spoiler because the car was so light in the front they could barely steer the things. But once it had that front downforce it needed pretty serious rear aerodynamic devices to keep it balanced, especially the extra back heavy and extremely powerful turbos
On a GTE or GT3 car it would lower cornering speeds and raise straight line speeds, but those cars have diffusers to generate rear downforce anyways so it could work. Most GT4s would need some sort of replacement though. FWD cars really like wings because of the less stable suspension setup they need to overcome their inherent low speed oversteer but aren't necessarily fast enough they absolutely need them.