Stupidity isn't about the individual developers -- it's about the incompetent decisions that Microsoft made about the browser. They decided that IE would be released only in-sync with new Windows releases. Vista troubles meant IE was effectively on hiatus between 2001 (IE6) and 2006 (IE7). Corporate interests were definitely keeping IE development back, but not as an intentional defensive move to sabotage the Web. Lack of competition in browsers during that period served as a pretty good demotivator, too.
"One thing we have got to change in our strategy - allowing Office documents to be rendered very well by other peoples browsers is one of the most destructive things we could do to the company. We have to stop putting any effort into this and make sure that Office documents very well depends on PROPRIETARY IE capabilities."
-- Bill Gates, 1998 a memo to the Office product group[2]
Seems like the guy in charge knew when to actively "stop putting effort into" things and intentionally sabotage the open web when necessary.
Ironically the reason I've tried my best to avoid MS Office is because they are not easily accessible by anyone. I once sent my CV as an HTML file along with a PDF. Still to this day, I prefer to send HTML and PDF over sending a Word document they only need an app that everybody uses, a browser.
What is more believable is that spell check in the browser is somewhat of an edge case relative to general browser usage (i.e. web consumption) which Microsoft was historically able to address by allowing plug-ins. They rolled it into the development of their plug-inless browser and rolled their plug-inless browser into their not quite so backward compatible OS release.
I suspect that the corporate interests have long known that IE is not a sales critical feature.
You're telling me that you actually believe that developers at Microsoft pick and choose what features they include in a browser?
You can blame software designers at Microsoft for that decision (or lack of decision), but I'm fairly sure that dev's at Microsoft are on the "fulfill the design" side of developing...
Agreed. I usually use the version of Hanlon's Razor that substitutes "incompetence" for "stupidity." Not that they didn't understand what was at stake, but made a series of bad decisions.
