The factory setting probably has alot more variables factor in such as crash test results, costs, wear, etc.

In racing we use toe to increase mechanical grip especially if you don't have the aid of aerodynamic downforce. When the left and right tires fight for direction, the tires tend to dig into the surface more, but of course there are limits to this, one being scrubbing speed on the straights.

Again, that's why I like suspension tuning so much . . . it's an art.