Speier stated that DD trusted his personal instincts over everything else. It did lead him to being a very successful GM, but it seems like he should have probably dialed it down at least a little bit. Apparently, it wasn't a very great place to work.
Side note: Speier's book was written well before DD was let go so it's not just sour grapes. https://www.amazon.com/Homegrown-How-Built-Champion-Ground/dp/0062943553