Or buy a Windows Laptop with far better graphics performance in a 13” model if so they desire. Better specs all around.
Only the GPU would be superior due to using nVidia. The rest is equal in the best case or worse. Still no Windows machine with four TB3 ports w/ USB 3.1 gen2. Battery life in the Windows world also tends to be inferior.
And of course this is without taking into account how many people downright prefer OS X. Many wouldn’t buy a Windows notebook no matter what.