One of the original reasons for positive camber was the wheel bearings. The inner bearing was larger and could take more load than the smaller outer. Positive camber shifts the weight to the inner bearing. This was in the very old days.The Germans went to negative camber way before the US did. Negative camber is the only way to go for daily drivers, and all cars. Tire wear is superior.
There is not 1 downside to negative camber on a street car.