As far as I know they are directly coming from Dell. That's the "breaking" part of this manual, that a retailer as big as them are trying to explain how to get rid of Windows and just install a Linux distro.
They have been selling Ubuntu on laptops for years now, you used to be able to get it on low end laptops like the vostro now days it seems its reserved for developer editions of their xps line only.
I have a Dell Mini 9 that I got for >$200 years (2009?) that came with Ubuntu that I still use regularly. Now it's running Puppy Linux (Slackware based) though.
