In a Tweet last night he wrote: "Improving Wine for Linux gaming seems like a better plan than lobbying individual game developers for native ports. Why the hate?"
For years id Software was very friendly towards the Linux community with releasing native clients of their games such as Doom 3 and Enemy Territory: Quake Wars. They also continue to be open-source friendly by releasing the code to their id Tech engines once they have no longer have any commercial value left to the company. However, with id Tech 5 and its premiere Rage title, no Linux port is being pursued. Even for the "Doom 3 BFG" update to the original game, they decided not to port it to Linux.
Carmack and others at id Software have expressed that it hasn't been too commercially viable bringing their games native to Linux. Now Carmack is promoting Wine for running Windows game binaries on Linux.
In a follow-up response on Twitter, at least Carmack did say, "Linux steam is a great thing for the platform! I hope there are some big hits." He also responded to another user with, "obviously a good native version is better, but emulation could bring thousands at a somewhat lower quality."