ignoring your frankly unnecessary sarcasm, I'd have to point out that some of us are held to the expectation that websites should look almost the same in older browsers. My previous employer, for example, required full support of all features in IE7, and that the product should even bear some resemblance to a website in IE6. In that situation (combined with AJAXed content making polyfills difficult), flexbox isn't usable. I'm sure I'm not the only one who has been in the situation of having to support non-bleeding-edge browsers.