This Carmack fellow seems to have his head up his ass.
..snip.... Lets also not forget how some companies, namely Blizzard, have banned players because they misinterrepted their playing through Wine as cheating.
Two good points. Carmack should know better. Wine is in no state to provide a clean, fast and reliable gaming experience. And it isn't as though people/companies haven't tried (Cross-Over/Cedega anyone?). To bring an acceptable experience in Wine (or any equivalent alternative), you would need to devote development effort because, as I am sure many here would know all too well, getting a Windows game running on Linux via wine is frustrating and often disappointing experience. I would speculate that the long term development effort to Wine as a multi-platform strategy would very quickly surpass native ports.