Seriously though, you have to have an initial browser to be able to get the browser you want. Of course a company will make that initial browser the one they make themselves. I've never understood the outrage over this.
Not certain if Ubuntu has a browser built in, but I would say that in this day and age, if GTK+ doesn't have any native components for rendering HTML then that would really stand out. It's considered an essential feature on every other platform's GUI toolkit. Just try removing WebKit from Android or an Apple OS, or pulling Gecko out of a Firefox phone.
The last exhibit would be Microsoft scrapping their plans to ship a version of Windows 7 that didn't include IE. (Though I imagine the rendering engine would still be needed - gotta display help files somehow, after all.) Turns out manufacturers didn't want to carry it, because nobody wants a computer that ships without a web browser anyway.