Blame Apple for making 32 bit games impossible to run on newer operating systems and requiring you to pay them just to make a working build of anything. Apple makes games on mac less accessible for developers by trying to run their mac games the same way they run the iphone app store.
This is not true. No engine can develop for macs without going through Xcode. It's possible to build a game on some engines that will run on your own mac, but other users will be unable to install your game unless you have an apple developer certificate. This requires the developer to be enrolled in the Apple developer program, which has a monthly fee associated with it.