Earlier quoted context omitted.
Maybe you are more accurately describing it. Some of them also say that free OSs are often behind on Mac hardware anyway, even on Intel. But the implication that I read into it is there's little reason to do it.
No big mystery here, people who buy Macs, prefer MacOS and don't see why you'd bother with Desktop Linux in general. I'm personally interested in Linux on the Mac as a curiosity and as an alternative in case Apple ever screws up MacOS so much I feel desktop Linux is the least bad alternative.
There have been other times when I thought apple hardware was more interesting than macOS. I don't think macOS is bad per se. There are times when I find it pleasant and times when I would greatly prefer something else. The attitude we're describing -- why use Linux when there is macOS?? -- strikes me as a little odd, because there is a built in hostility and assumption that everyone shares the Mac fan's opinions and preferences, universally and in all circumstances.