#1. The Fiend's biggest weakness

Believe it or not, there was a time when WWE repeatedly teased that The Fiend had a weakness, but never followed up on it. In fact, WWE brought it up several times throughout the feud between The Fiend and Daniel Bryan, which is why not getting answer to that question was so jarring.
What was even more jarring however, was the fact that WWE had Goldberg destroy The Fiend in a squash match and took his title for good measure. Again, no explanation was ever given in storyline as to why Goldberg was the only one to defeat The Fiend, but that was quickly forgotten about too.
With that being said, The Fiend is a special kind of entity. He is someone that seems to be immune from losing relevance. Furthermore, he seems to be a character that the WWE Universe believes in no matter what, thus why the company was ultimately able to sweep the weakness thing under the rug.