Rear tire width requirements in relation to HP?

I am a little confused. A lot of talk about rubber compounds differential gearing, traction bars, pinion snubber's etc........... I thought he was going to drive it on the street. The only traction of concern should be when braking or making hard turns. All of this other stuff is just bench racing. How many of you are concerned with how hard your car is launching when you are just going to the store ? Really??