To give a counter example, I run Ubuntu 14.04 on a NUC with a Dell U2713H via displayport and a samsung 24 inch via HDMI. The whole thing was a matter of install, and be ready to go. No command line dances needed.

I think it comes down to picking hardware that is supported well, i.e. Intel stuff. Apple of course for the most part knows it's hardware and doesn't have to include a gazillion drivers for graphics boards of all make and model.