Why?
We can add a splitter and undertray as part of a "free" air dam.
We can add heat heat shielding and ducting as part of a "free" radiator.
We can add all kinds of bars and arms to the rear suspension as traction bars.
You should see some of the "sway bars" that are out there.
The fact is the rules say the following:
1. If something is free, you can make it do what you want so long as it doesn't perform a prohibited function. You can't for example use "free exhaust" to run a turbocharger.
2. But if what you are doing with your free item isn't specifically prohibited, have at it. Otherwise, the idea that "if it says you can you can" means nothing and things like splitters and brake duct hose (rule says brakes may be ventilated, doesn't say how) and heatshields and ducting built off of radiators and air dams (ever see the front of a well-developed 2nd Gen RX7?) are all gone.
Here, my wheel spacers simply happen to have studs, just like some folks ventilated brakes have hoses, or their radiators have ducting, or their air dams have splitters.