For me, for gaming, the full-screen console-like experience is part of the appeal. SteamOS has full-screen Steam, but it doesn't boot into it. Plus, Gamescope has some nice performance measuring/management tricks that regular Steam doesn't provide.
If you just want Steam on an OS then installing Steam will do fine, but it's no "real" SteamOS experience.
Another part of the appeal is how stable the updates are thanks to update mechanism (and locking users out of the system config by default so they can't break their Linux installs with outdated scripts from askubuntu.com).
If you just want Steam on an OS then installing Steam will do fine, but it's no "real" SteamOS experience.
Another part of the appeal is how stable the updates are thanks to update mechanism (and locking users out of the system config by default so they can't break their Linux installs with outdated scripts from askubuntu.com).