Why?Correct. You buy the set and don’t use the G (BEAD).
This is the 21st century. 4 string sets specifically for BEAD have been readily available for years. For less than the cost of a 5er set. When you buy a 5 string set for a 4 string BEAD, you're wasting money, and wasting the environment. (assuming you throw out the G string) A drawerful of G strings is only of interest to a robot stripper.