But by that point it was clear it was already dying and IE7 et. al. were introduced late as an attempt to catch up. During the period when the real bullets were flying, IE6 was actually a really great browser, just one that forced you into using a menu of Microsoft technologies because it didn't support the "standard" stuff. Remember that XMLHttpRequest, the basic tool underneath all modern dynamic web UIs, was originally a non-standard Microsoft invention.
And yes: eventually this proved unsustainable and innovation in the standards-based browser world eventually proved too fast for MS to keep up, and it lost.
But the tool that broke the back of that monopoly absolutely wasn't Firefox. It was Chrome.
Sure IE6 had many non-standard APIs, but even the fact that all hobbyist browsers back then were implementing tabs and IE6 never had that, speaks to its stagnant development. To be honest I'd prefer some things Google is now pushing through th W3C as standards to be left as Chrome specific APIs and leave the rest of us alone.
I mean at least we still have websites like this from over 20 years ago that still document the bullshit, people who weren't there CANNOT fathom the how despicable they were.
I think the biggest issue with IE6 was not the hostile moves Microosft did, it is that it didn't do anything. The browser was just frozen. That's why it was relatively easy for Firefox to take a marketshare.
Frankly, with some of the APIs Google are adding to Chrome, I'd rather they'd do a little less.