NTFS != HTML
Web browsers, help viewers, file managers, etc. all turn out to be special cases of a completely generic and reusable set of services for rendering and browsing information.
So here's your fallacy: You think that under the hood, all of Windows is a web page! That's a stitch.
Now for today's lession. Micros~1's stated reason for bundling IE into the operating system (aside from the bullshit marketspeak about "convenience for the customer") is to centralize HTML rendering (or, more accurately, their specific, non-standard flavor of HTML rendering) into a single place so that their ISVs can have HTML rendering as a system service; sorta like reading a directory or getting the system time.
(We pause while the rest of you regain your composure...)
Now, I don't need HTML rendering (which is also about 20K of code) integrated into my file manager, or my file system, or into timer services, or into any one of the rediculous number of things that Micros~1 has "integrated" HTML rendering into. And I certainly don't need HTTP protocol handling, or FTP, or E-mail, or ActiveX activation, or viral back-doors, in any of those things.
Now, if Micros~1 were, in truth, a tech company, they'd have created several small, replaceable DLLs, each of which would have contained a single, tightly integrated, loosely coupled, function set that did a single job (e.g. a Micros~1-flavor HTML renderer (Ghod knows we wouldn't want an IETF-compliant HTML renderer available on Windows!), an HTTP protocol handler, an FTP protocol handler, etc.) In fact, If you read the trial stuff, Micros~1's own engineers (you know, the guys who actually know something) complained on the record that piling all the crap into a single DLL was making their life more difficult, and causing yet another of Micros~1 constant, interminable schedule slips. But NOOOOOooooo... Engineering was overruled by Marketing, and the result, as they say, is history (and, of course, illegal).