Like 15% of my Steam library is playable on Linux, do you really understand what does FUD mean? or you just repeat it blindly when you read something you don't like about Linux?
Linux is not a good platform for games. Steam does a good job at improving the current state, but it's far from ideal. For many people it matters, and expressing their sentiment is far from being FUD.
Steam's Linux game library is quite un-impressive when you count in how poorly many of them including most AAA titles actually work on SteamOS and other Linux distro's.
Allot of them aren't natively ported by rather use middle ware like the one offered by Transgaming which is no more than an optimized version of Wine.
Not to mention that many of the "AAA" titles will have either a much higher system requirement for Linux or outright just not support hardware which is supported on Winodws.
For example Borderlands The Pre-Sequel doesn't supports AMD cards at all on Linux and has double the minimum requirements of the Windows version.
So sorry while Linux gaming has come a long long way it's still not something that you can call viable for "Gamers".
If you only play old titles and indie games you are probably fine tho...
But maybe it's just more fun to spread FUD?