[tshaddox]

The web is (or at least was) document-first, yes, but Google Docs is an extremely heavily-featured WYSIWYG word processing and desktop publishing application that happens to be distributed on the web (in addition to other platforms). The fact that you're (sometimes) using Google Docs to generate a simple document that could easily be represented with simple HTML does not imply that Google Docs itself is a natural candidate for being implemented with simple web APIs like DOM.

Now, I think if the contentEditable API were significantly more robust and consistent across browsers, it could have been viable to build extremely complex WYSIWYG editors using the DOM. Most of the popular rich text editor libraries for the web are essentially compatibility layers around the contentEditable API that attempt to normalize its behavior across browsers and present a more robust API to the developer. These libraries are popular and do work pretty well, but based on my experience with them it's no surprise that an app as popular and extensive as Google Docs would constantly bump into the limitation of this approach. (My impression is that Google Docs never used contentEditable and instead wrote their own layout and editing engine that manually rendered out DOM, and they're now changing that to render out to canvas.)

[DaiPlusPlus]

> My impression is that Google Docs never used contentEditable and instead wrote their own layout and editing engine that manually rendered out DOM, and they're now changing that to render out to canvas.

Back before Google owned Google Docs, it was a non-Google company and website called Writely, and their website was basically a document-hosting system tied to a fairly stock `contentEditable` editor.

This was around 2005 - back when every web-application development client would insist that users have WYSIWYG/rich-text editors - of course they had no idea how WYSIANLWYG (What you see is absolutely nothing like what you'll get) those WYSIWYG editors are like.