Does SteamOS count as something Carmack would discourage as well? Yes it's a Linux-based system and yes even based on an existing distro, but it is a purpose-specific OS and it seems like it's working well for Valve and people using it to play Windows games without Windows...

End of the tweet:

> I can only really see a new general purpose OS arriving due to essentially sacrificing a highly successful product’s optimality to the goal of birthing the new OS