> Straw man. The only people I see bringing IE6 up in this discussion are those trying to create a false dichotomy between the now-trimonthly release schedules of Firefox and Chrome and something bad.

It's not a strawman. Why do you think IE6 is still around? It's not for the grandmothers who don't know how to run Windows Update. It's for corporations who demand that Microsoft support an ancient product because they're too lazy/cheap/incompetent to upgrade their internal apps to work on modern browsers.

Corporations want indefinite support on every piece of software they use (and why not, I guess). The question becomes how long does it make sense for vendors to support a product. When you're talking about a product that needs to be upgraded frequently to continue to do its job and to maintain security, I'd say the answer is "not very long".

> Well, if you want browsers to be taken seriously as a platform for running software applications and not just viewing static sites with occasional interactive features, then browser had better become that long-lived.

You're the one creating a false dichotomy here, pretending that the only options are to build for a stagnant browser or to not build at all. The browser is not the platform, and that's what you don't get. The web is the platform. If you built a web app for Firefox 4, it's going to work in Firefox 5. The platform hasn't changed. It's gained some new features perhaps, but the original functionality is still there.

> Do you have any idea how much investment Microsoft makes in keeping each new version of Windows backward compatible with software and drivers from the last version (or, more likely, the last several versions)? There is no way they would be the dominant force on the desktop today if they had gone around releasing point updates to Windows every few months and arbitrarily breaking other people's software that was built on their platform.

An interesting point of comparison would be to note that Firefox 5 is backwards-compatible with Firefox 4. Unless you choose to use bleeding-edge beta functionality, your sites will still work just fine. Mozilla (and Google, and Apple, and Microsoft) work really hard to maintain backwards-compatibility in their browsers. You're pretending that upgrading to FF5 means that everything written for older browsers will stop working. We both know that's not true.

> Even your three year figure is telling. If Windows 7 hadn't been able to run existing applications written in the XP era, Microsoft would probably be toast today, having blown two big OS releases in a row and lost the confidence of the developer market. Three years is within the typical lifespan of a single PC in an office environment, particularly these days when IT departments are seriously questioning the value they get from spending time and money on the upgrade roundabout and paying for all these subscription plans. Everything else that came with the PC still runs three years later and still lets people get their jobs done. Why should browsers be anything special?

They aren't special. Firefox 5 will run all the same sites as Firefox 3.0, and it will run a lot more as well.

> Your final paragraph is just outright denial. Microsoft can and do patch security and compatibility bugs in Word all the time.

Of course they patch bugs. I never said they didn't. That doesn't mean the Word Processor model makes sense for browsers. I'm using Microsoft Office 2008. Should I also be using Firefox 3.0? I haven't upgraded Office because it costs money. I have upgraded Firefox because it's free and easy. Browsers are no longer shrink-wrap software, and treating them as if they are is ridiculous.

> They just manage to do it without changing the UI, introducing new file formats while obsoleting ones that were fine just six months ago, and breaking a couple of key features that they don't care about because only 5% of users need them.

Can you point out what FF5 has done that's so terrible and backwards-incompatible?

Edit: I guess there are some add-on incompatibilities, and that is something that they need to address moving forward. Frequent drops are fine, but should maintain compatibility.