>>28701033
We are talking about downforce in corners, to keep rear well planted when cornering. Wing has no use at speed, in fact it reduces top speed.
Meanwhile spoiler makes difference in way how much power your car uses at speed.
Car X(without spoiler) travels at 100mph and lets say requires 200 horses to overcome drag behind it. Uses all 200 horses to reach and keep these 100 mph.
Car Y(with spoiler) travels at 100mph and lets say requires only 170 horses as spoiler already reduces drag. Now with extra 30 horses you saved, you can push it to 105 mph. This way with a spoiler your car can go faster than without.
Wing is needed only to take corners faster, for the cost of total top speed.
Spoiler makes car go faster but does not improve cornering so much.