The point is that that market is tiny compared to the people that buy iPhones. I also think Apple is doing good things on turning the iPad into a general purpose computing device. For my use cases (ssh somewhere to do work), it is way easier to manage than a laptop, and smaller. I imagine that as the product improves more people are going to make the jump, leaving MacOS in a weird place. (I switched from a Surface Pro 4 to an iPad Pro as my "laptop" and I am much happier. I still use a Windows workstation for everything that can't be done by ssh-ing to a Linux box, though, and of course prefer dual monitors and a mouse when I'm not travelling.)

Of course it is "tinier", because the PC market (and Macs are PCs) is much smaller than the phone market.

And has been shrinking since 2010... must be a coincidence as Apple introduced the iPad that year...

Source on the dominating above $1000?