The IIgs was released a year or two after the Mac. It was at a time when the Apple II was still a hot seller, and Apple had to take advantage of that. It is also worth considering that the early Apple IIgs OS was nothing like the final product in the late 1990s. From the little that I've seen, you had ProDOS 16 and a little B&W program launcher that was very crude compared to even the Finder on early versions of Mac OS. The TOolbox had not bloomed into it's full glory either (in essence, you were stuck with the ROM Toolbox).