I definitely remember takes in the genre of "who cares if IE is never updated. What else could you possibly do on the web?" back when websites were mostly static, JavaScript was still a toy, and all the people who could imagine better were trying to convince everyone to switch to [Phoenix, Firebird, Firefox]. Microsoft had the inspiration for XMLHttpRequest right there and couldn't see past its Windows-centric strategy.

There's an alternate timeline where Microsoft leaned on anyone implementing it. We never would have gotten as far as Sun suing Google over the Java API because no one crossed Microsoft.

No AJAX. No web 2.0. No SPAs. It would be a different world.