Perhaps one of the reason why people are still capable of getting an acceptable Internet experience from IE 6 and 7 is because Flash 10 (and 11 for IE 7) supports them.

Thank goodness that there is a strong traction behind HTML5 stack, and the industry as a whole is less reliant on Flash to deliver good UX.

Without Flash, the capability of these older browsers will be reduced, and I'm sure they will get abandoned at an even higher rate.