It's not even that much more involved, just tedious. The serialization/deserialization of X requests and responses is fairly straight-forward (it could be more straightforward - it's not a very nice protocol, but it's also not difficult), as the article also shows, and it can be made more compact than that with a couple of helpers.

The biggest pain in doing "raw" X is the async nature of the protocol - to write a robust X client you really want an event-loop driven approach that embraces that like XCB does, instead of trying to paper over it (like Xlib did).