The Wordsmith's Forge

I think it's because he's one of the smartest guys the human race has ever produced. Okay, great. He has a brilliant mind. But take him outside his areas of expertise and he's just an ordinary genius, not an expert. Also, the tighter someone's field focus, the less experience they have with interdisciplinary work. On some topics, that's a nasty handicap, especially if you aren't already aware of the many ways it can bite you in the ass.