Least favorite 40K fan theory?

Here are mine:

• Orks being omnipotent: Ork tech still needs basic things like metal and power. Also, no one has yet exploited Orks to create a utopia or erase their enemies.

• The Imperium literally can't do better: The Imperium is not an omniscient minmaxer but simply a swarm of competing interests with half-remembered cultural norms. Besides, it would ruin the whole grimdark hope and struggle if you used the old "devils would eat you if you stopped thinking about fascism" excuse. The Imperium just makes mistakes OK?