That applies when you build websites. But when you build web apps, you care more about providing the best optimal experience for the up-to-date browsers and if you have enough time you can provide a graceful degradation for the old browsers. But most of the time it depends on what you've been ordered to build and which users you want to focus.
Keyword: enough time. Spent two day working around a firefox outline bug only to have it break on mobile safary because their absolute positioning of pseudo elements is relative to the parent and not the element.
Browsers are making my day to day work miserable. I wish O could target a reference css3 platform and browser specific bugs be damned.
