The average user does not give a shit if it is Xubuntu, KDE openSUSE, Some basterd Debian version with GNOME or RedHat with Enlightenment.
They do not care. All they care about is pre-install.
They bought a Windows phone; next they bought an Iphone and then they bought an Android. And next week they will buy the next new thing.
Pre-install is what it is all about. For the majority of people going from Windows 8.1 to Windows 10 is just as difficult as finding the Internet Icon in any other desktop management system.
Apple and Windows do not care for the few million people who have an OS preference. They are not their market.