Disagreeing with Orwell

One of the rules stated in Orwell's paper was never use a metaphor, simile, or other figure of speech which you are used to seeing in print. I think its fine to use a metaphor or simile. Especially in creative writing similies and metaphors are important and they help make the imagery vivid. He stated in his paper one of the two problems in the example he used was it's staleness of imagery. He is sort of contradictory in this sense and it confuses me. That is all.