You also can't leave a non-mobile operating system without pain. Mac to Windows: pain. Windows to Mac: pain. Windows to Linux: pain. Linux to Windows: pain. Linux to different Linux distribution: pain. Mac to Linux: pain. Linux to Mac: pain.

Some pairs might have lesser pain, such as Linux to different Linux distribution or Mac to/from Linux, if you mostly stick to more basic command line stuff, but the same is true for mobile device operating systems if you just stick to the basic mobile phone stuff which would be telephone, SMS messaging, camera, calendar, web browsing, and non-cloud syncing.

Good point but I think that it's another self-inflicted pain. Everyone can open this website no matter their operating system, architecture, etc. Why is that?