He did a book ("Designing Web Usability" I think) with an unconventional layout and it clearly hadn't been user-tested as it had a flaw (text too close to the binding) that made it ironically hard to use.
I think he was on point with a lot of stuff, but I've been a bit jaded ever since!
I thought the same thing of his website when he first hit the scene. Great info, but the design was so bad it made it difficult to read. It was quick though, and today’s reader view would have fixed that issue. Being usable doesn’t mean zero design; everything needs to work together.
It’s kind of ironic that Nielsen’s site and even his book layouts were often frustrating to use. But maybe that proves his own points.