I disagree. IE6 doesn't support a lot of standards that other browsers supported, mainly due to not keeping up with changing standards.
>If it wasn't for the law, we could forget about the blind too?
Note that I said "being blind is rarely a choice", implying that we should code for the blind because they did not choose their limitations. If you're forced to use IE6 in a corporate environment, it's because the designer of a web app wrote it for IE6, not for "the internet Tim Berners Lee had in mind". No one is forcing you to use entertainment-based web apps at work, in fact your management might discourage it.
>I don't think that was the progress that Tim Berners Lee had in mind. A progress where HTML documents from the HTML5 era become inaccessible to later generations.
And you think that the designers of floppy disks intended for them to be thrown out when USB drives came into existence? THIS IS PROGRESS This is what progress does. Technology changes. Don't code for current technology, code for maintainability. If your code works on IE6 but is broken in newer browsers, your code is broken by design. There is a standard, and code that follows it will work in browsers that respect it. IE6 does neither.
You honestly seem to be arguing that IE6 was a perfectly compatible browser and was the pinnacle of browser design. I think you'll find a lot of disagreement, even from Microsoft themselves. We know enough about security these days to know that not upgrading is a bad idea.