Earlier quoted context omitted.
My thoughts exactly. Currently, gaming on Linux was fairly on the rise, since Steam supported Linux as one target platform and advertised it fairly substantially. If Steam renames all "Linux" entries as "SteamOS" and pushes general Linux to the sidelines, all that progress is lost.
"Linux" isn't a platform, "SteamOS" is though. Having an undefined "general Linux" is impossible for them to support, especially since there's no real definition of a platform, just a kernel.
If "SteamOS" becomes a target in the Steam app, this general "Linux" label may be pushed to the sidelines, and since SteamOS may contain more proprietary parts than general Ubuntu does, we may find it much more difficult to run the games on any distribution other than SteamOS itself. That was my point.