It also works as a cell-phone OS (android), a television OS (ruku TV), a router OS (pretty much all of them), it's almost taken over education (Chromebooks), and embedded (Raspberry PI). Calling it a "server OS and a workstation OS" in 2018 is just plain wrong.
To diss Linux, we need to limit the perspective to only PC gamers. Thanks to Valve (Steam), cross-platform engines, and Vulkan; games supporting Linux are more numerous than ever before and the future looks even better. With all of these factors in play, it is reasonable to think that Linux gaming will be worth it in the the future.