[SteamOS] PSA: What SteamOS is and What it is Not

Overview

A short set of statements from Reddit user RubyKuby. All credit for this post goes to that individual.

Get on with it!

Hello fellow brothers and sisters of the glorious PC gaming master race. Lately, I have noticed a lot of misconceptions about SteamOS and (per extension) Linux. I wanted to make a PSA-style post to clear up a lot of those misconceptions.
History

Prior to 2013, gaming on Linux looked a little bleak. Humble Bundle had been pushing indie games towards Linux, but none of the big titles ever really appeared on the platform. This changed when Valve released Steam and some of its own titles for Linux in February of 2013.
Steam for Linux was targeted at Ubuntu, a desktop Linux distribution targeted at “human beings”, AKA non-techies. For the sake of simplicity, I will continue using Ubuntu as synonym for “desktop Linux”.In September of 2013, Valve announced that they were working on SteamOS and Steam Machines. SteamOS is a derivative of Debian, same as Ubuntu. This means that the innards of SteamOS and Ubuntu are practically the same.

But Valve created SteamOS with a vision, and that vision was a PC gaming experience in the living room. Basically, Valve wants to tackle the current console market (XBone, PS4, Wii U) with a PC approach. They could not simply slap Windows onto their Steam Machine consoles for several reasons:

Windows is pricy.

The Windows desktop interface does not work in the living room.
Microsoft showed the entire industry what seppeku sudoku looks like when they released Windows 8. Valve doesn’t want to be solely dependent on Microsoft for their platform.
Microsoft posed a potential threat with their Windows 8 Marketplace, cutting out the middle man (Valve).

So they opted for their own distribution of Linux. This gave them the primary advantage of full control over the platform, and the ability to use a console-oriented graphical user interface.
This graphical user interface is called Big Picture. You can try it out yourself by clicking on the console icon in the top right of your Steam window. SteamOS boots straight into Big Picture much like you would expect a console to boot straight into a console-oriented GUI. Ubuntu, on the other hand, boots into a traditional desktop environment. It would be exceptionally clunky if you had to use Ubuntu’s desktop environment in the living room with a controller.
The misconceptions

And this is where the misconceptions arise. For some reason, a lot of people forget that SteamOS is simply Big Picture – nothing more, nothing less. If you wanted to, you could make your Windows, OS X and/or Ubuntu installation to act identically to SteamOS by forcing the operating system to boot into Big Picture.
Per extension, this means that SteamOS’ sole use case is in an environment where being limited to Big Picture(*) is desireable. On the desktop we all know and love, that would be disastrous. We would lose the ability to run all of our favourite non-game applications, we would lose access to full control over the file system, and we would lose all the things that make PC so powerful and flexible.

*So here’s the catch: SteamOS has a desktop mode. You can leave Big Picture, and use SteamOS just as if it were a regular desktop. You can run all of your favourite applications provided they have a Linux version, and you have precise control over everything on the system. This, along with the ability to use whatever hardware you prefer, fundamentally differentiates Steam Machines from the current consoles: The user is in full control over everything.
But if SteamOS has a desktop mode, why not simply use SteamOS on the desktop? There are a couple of answers. The first answer is the simplest from a user perspective: You don’t want your desktop to boot into a console GUI. The second answer is a little more complex, but it comes down to this: SteamOS is not designed for regular desktop usage. The desktop that you can access in SteamOS provides the bare minimals: A web browser, a file manager, some viewer (image, PDF, video) programs and a settings manager (not exhaustive, but you get the idea). Ubuntu, on the other hand, provides a gigantic suite of desktop applications. Not only that, but everything about Ubuntu is specifically tailored for desktop usage.

The only reason that SteamOS allows you to access a desktop shell, is to provide you with a working space to tinker your Steam Machine in a way that consoles cannot offer you. Don’t like the compositor? Replace it. Want to change boot parameters? Go right ahead. Fancy to use your Steam Machine for something that Big Picture doesn’t offer you? Go crazy, install a permanent Minecraft server for all I care. The desktop makes this easier for the grand majority of people who don’t want to go into the terminal.

SteamOS is a console operating system that offers all the best that PC has to offer.
Where does this leave Ubuntu? Well, for any system that is not permanently underneath your TV, you can use Ubuntu and play the exact same games that SteamOS offers, because they share the same fundamentals. Of course, you can also use Windows or OS X; whatever you fancy.