Technically the iGPU can run the game, it just won't run it at any level worth playing, which is why the MacMini and Macbook Pro/MacBook Air tends to not meet the requirements. Once you consider the cooling requirements of running a laptop maxed out, you'd quickly realize why you shouldn't use a MacBook Pro (or any other "thin+light" ultrabook style laptop), it will melt.
Gaming laptops still need a switchable nVidia/AMD GPU to run, and that's why only iMac's with those are considered playable, even though the performance of most of them aren't at a level that is considered playable. (eg 5K iMac, but you have to run it less than fullHD resolution.)
Because the Mac Version is just a wrapper around the PC version, that adds an overhead that doesn't exist in the PC version, and iGPU parts are just not going to cut it.
