14 DAY TRIAL // Everyone has been wondering why SteamOS isn't based on Ubuntu, and the answer to that question might have been provided during CES 2014.
According to a report on German website heise.de, Valve had to replace Ubuntu as the base system at the last moment and switch over to Debian. The invoked reasons are “legal issues,” but that could mean a lot of things.
The most likely scenario is that Valve might have had to pay Canonical some fees. If you make a Linux distro based on Ubuntu and you offer it for free that’s fine, but if you are going to make money off of it, Canonical might want some slice of the pie. It's their distro and they put a lot of work into it.
Ubuntu is based on Debian and you might think that's not a big deal, but the truth is that Ubuntu is a lot more suited for games than Debian, and it showed. SteamOS is clumsily put together and it's a long way off from a friendly solution.
Ubuntu is a much more appealing, user-friendly Linux OS, and it has a large developing community behind it.