No its like saying Home Depot shouldn't sell power tools to children who don't know how to safely use them.
Unless the web server displays a huge red message every time it is run saying "Don't even think about using this in production" you can bet that it will be.
20 words of that manual were dedicated to letting people know its not for use in production. Un-highlighted and buried at the end of a paragraph that I initially skimmed over and didn't even read. No attention is directed at it in any way.
So the server outputs a message. Great. Is it huge, red and says "do not use me in production"? No. Its a standard version banner.
Really? Look at the documentation page. The first thing you see is a huge chunk of text with absolutely no highlighting to guide you. Most people would just skim their eyes over that, and my attention gets drawn to the list of MIME types because it looks different.
A simple bold tag immediately draws focus and ensures that the huge majority of people who view the page get the important message. That's not being hard to please, it's just common sense.
I don't the person is being a pain. People will not heed a warning that is not clear and apparent. It's like the warning on the side a hot cup of McDonald's coffee. It's not paid any attention if it's not really, really, ####-->REALLY CLEAR<--#####.
I am of the opinion that it's simpler to write a basic PHP file than it is to configure Apache, Nginx, Lighttpd. I'd think that the majority of people running WordPress (likely the most distributed PHP project) are doing so on shared hosting, and not likely to want to or know how to configure their own server. The type of person interested in the built-in web server (a decent feature in my opinion, and comparable to `rails s`) is knowledgeable enough to know that the built-in web-server will not cut it for production traffic.
Unless the web server displays a huge red message every time it is run saying "Don't even think about using this in production" you can bet that it will be.