Those browsers are not alike. If you follow standard advice - valid HTML, progressive enhancement, unobstrusive Javascript (or fallbacks where needed) - Lynx will render your snazzy 2011 page with the same fidelity as a 1995 Geocities page, and the result will be perfectly usable. IE6, though, will not only ignore your CSS3 stuff, but also completely misinterpret the things it does "understand".
