Now, my first thought was that something had gone wrong with the reporting software I was using. There was no explanation, I was just on the Firefox page. My second thought was that they had done something almost clever -- build up traffic then force all traffic to a revenue share deal to make a couple bucks.
But, no, it was just that they didn't code for Internet Explorer 6. They didn't bother telling me that I needed a new browser for their site by giving me an alert or a pop-up page, instead they just forced me to use their browser.
W3C stats shows IE6 still at 19.6% of the market as of December 2008 (just last month). If we assume there are 1.5 billion people online, that means they are ignoring 294 million people. Granted, they aren't all going to be interested in what people are saying on Twitter about the weather, but, talk about limiting your audience right out the gate -- 20% BAM, gone.
It's like saying, "No darkies allowed at the bar." And forcing me away without explanation is just that, shoving me off into a corner.
There are legitimate reasons people may have older browsers, including they aren't allowed to install anything else but more importantly, personal choice. If I choose one browser over another, and certain functions don't work, then that's my call.
Your website should work for any major browser. That's the beauty of the web, I don't have to install anything; I just open a browser, click on links, and see the stuff I want to see. Sure, you might have to install plug-ins like Flash, but it's already installed in over 90% of the browsers, so writing for Flash is pretty safe.
It's a matter of respecting other people and the choices they make, or are forced into for reasons beyond their, and your, control. Anytime you insist they do something that's not part of the core goals of your website, is a time that you're forcing them away from you.