Thread:VisualEditor/Feedback/JavaScriptless experience/reply (3)

What TheDJ said, essentially.

To be fair to the browser manufacturers, our needs are significantly more complex than basic ContentEditable. The vast majority of VisualEditor's codebase (of which there is a lot) is for providing nice ways to edit content that doesn't exist in the ContentEditable world (like images or templates) and stopping browsers from letting you do things you can't (like changing the colour of the border on a thumbnail'ed image). There's also the entertaining litany of browser-specific quirks and bugs that we have to work around in this area, which is only semi-standardised.

As so often, if a quick glance at something means it "seems trivial" when people are spending several years working on it, you've may not have looked deeply enough. :-)