SphereCast in standard Character Controller?

Hi , I was looking through some of the standard assets in Unity to learn how some of it works. When looking in the standard firstperson character controller script I saw that they used a SphereCast to alter how the character move. For fun i tried to remove the SphereCast from the script and see how the character would react to different scenarios (terrain, slopes and that kind of stuff) and i can't find a single scenario where it moves differently with the SphereCast and without it. So am I blind at it does really change something? Or does it do something complete different than I think? Thanks,