>Microsoft actually stopped development of IE, saying the job was done

Despite being a technology enthusiast who was paying attention at the time and who heard this when it happened in various discussions and articles, now some twenty years later this is hard to source!

This is one account: https://slashdot.org/comments.pl?sid=171546&cid=14288661

Mozilla lists it as such on their timeline (May 31, 2003):

https://wiki.mozilla.org/Timeline

Microsoft Drops the Ball with Internet Explorer: https://web.archive.org/web/20050506233847/http://www.window...

So it wasn't that users refused to upgrade their installations of IE, it's that Microsoft insisted for a long while there would be no IE releases past version six, since it was now a part of the operating system and the team they had had had been disbanded to work on other parts of Windows and Office by that point. It was only when enough bugs were seriously impacting Windows and the emergence of Firefox and Safari that they started taking serious aim at fixing those bugs and releasing later versions of IE, seven and so on..

The job was done in terms of market share achieved, and thus they divested their resources elsewhere. The mistake was to not invest more seriously in further development when Chrome gained popularity.