Honest Question: Brain Dead Cards / No Skill Decks?

When someone says a card or deck is brain dead or its no skill, is it just because they get their ass whooped by it? I see a lot a messages about brain dead decks and or cards, but when I check Royalapi, many of these cards and decks are low rated. Additionally, you don't always see the brain dead decks used by the top ranking players.

What are the criteria that make a card or deck require no skill or brain dead? Where can I find the stats to verify these claims? And if these decks and cards so easy to use, why isn't the leader board dominated by them?

I remember once upon a time, when I first started playing this game, I thought X-Bow and 2.6 Hog Rider where no skill decks...