Now I think most all-flash sites are Not Scottish. But if someone decides they want their e-commerce site to be flashier than anyone else's, it's their site, they can do what they want. It's not like people are taking working sites, re-writing them with new technology that doesn't degrade well in older browsers, but still looks the same in new browsers as before the change.
Are you suggesting that when someone writes a new version of their site using a new technology, that they should also keep the old site up-to-date and in sync with the new site? Because that's the only way to introduce the new features without locking out users of older browsers.
 I just realized, you sound like you're talking in general terms about a specific instance. What site or sites stopped working for you when they redesigned?