Microsoft insisted that the OS needed the internet explorer executable, not only the rendering engine components. You couldn't even run windows update without it opening IE - in order to load a native ActiveX component that then performed the work. They where desperate to make everything depend on IE without a plan of how to make good use of it, which shouldn't be surprising, back then any complex use of IE would have blue screened the entire system.
> vindicating Microsoft's technical decision.
Imagine a ChromeOS based on IE5 and tell me why I shouldn't break down in hysterical laughter just thinking about it.