The manual on my 98 Firebird says to push it when starting out in icy or slippery surfaces. Living in Florida where it rains frequently, I use it when I'm at a red light on rainy days. It really does help to have more traction. I turn it off after about 1 minute after starting.
--It starts vehicle in 2nd gear instead of 1st gear, so there is less torque at rear wheels. This enables it to get grip without spinning the tires as easily.