That functionality these "components" need that is in no way related to browsing the World Wide Web
That's funny, I see them all as being nearly the same thing. It's all about viewing structured information\ufffd- Web pages, documentation, administration settings, directory hierarchies, etc. The only thing that's different is the mechanism by which the information is retrieved. Once the raw data is in, the process of rendering and browsing it is pretty much the same for all the things I've mentioned, the differences being supeficial UI tweaks. Perhaps you're simply not very familiar with the way IE's functionality is partitioned and reused? Come on now, admit it.
Remember, a web browser is used to... browse the web! [...] There's no efficiency in welding components that have nothing to do with browsing the web to a web browser. Get it?
Think, man. The thing that makes that web browser different from a help viewer is the built-in HTTP client, which amounts to about 20K of code. The rest of it is just begging to be reused in about a zillion other places. 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. Are you sure you're not just pissed off that Microsoft realized this first, and that now the Navigator, KDE, and GNOME teams are playing catch-up?