I imagine the reason most people use WordPress isn't because of the authoring or editing — most of which can be replicated easily using things like TinyMCE — but the ecosystem of themes and plugins. Your technologically-inept client has access to a vast number of free, cheap, and easily installable themes to style their website whatever gaudy way they want.

There are plenty of better publishing solutions in terms of codebase, and there are plenty of solutions that offer equal or better user interfaces, but none that bring the ability to choose from hundreds of thousands of themes to style a website, which is the main focus of your average blog publisher.