You'd have to be literally drunk to think that's a good idea.

That's actually what the people at Valve did (GDC 2013): https://developer.nvidia.com/sites/default/files/akamai/game...

Performance improved as a result. The number they give is ~20%. The other nice thing was that you could use D3D10+ on Windows XP...

Yet there are DirectX state trackers in Gallium3D. I doubt that Gallium developers are drunk all the time.

They're not optimal, but they do work. (The reverse exists too; this is how the D3D build of my game engine works for targeting Metro.)

Drunk on WINE?