@magicalclick: One word: Enterprise.
Big companies (and governments) that pay millions of dollars for contractors to build internal web-sites get really pissed off when the website breaks because Google or Mozilla pushed out an update that had a minor but breaking change in the graphics engine.
These websites might be relying on ActiveX controls and pixel-perfect positioning based on entirely broken HTML that was made six years ago, but you'll be damned if you can find a CEO that understands that and agrees that the website needs a $100,000 makeover just to make the website look the same as it does now with no feature improvements.
This is why all big companies use Internet Explorer. IE does not change how it renders pages except at major version changes. And as an IT-administrator you get to test it across your enterprise and choose when to deploy that major change.
This has been hashed so many times before.
A thing like that is not a website and should not be called a website! And these developers/managers are holding it wrong (actually held, since I don't believe there are people like that today).
EDIT: So, we agree basically, but my take is that the rug should be pulled from under them, their projects are not websites.