Without the editor it’s not a “Feature”, it’s a method. If they were to ad this method to the editor, then they would call it a feature of the editor.
Anyway,
Yes, it’s possible to do everything you can do in the editor without the editor. The editor is just a more user-friendly interface.
If you’re good with html, css, php, javascript, and all that, then you would have much more control over how you lay out your site/blog, but you’ll also have much more responsibility, security issues, dynamic linking, post tracking, and all the stuff that goes into a dynamic website that you don’t see from the Post Edit Box, because it’s already coded into your theme.
With the Editor you only have to focus on content writing, and some minor formatting.