Don't agree with Number 1

I don't agree with number one "Never use a metaphor, simile, or other figure of speech which you are used to seeing in print," because even though it may seem wrong to the author, I personally think if you can use them to deffend what you are saying then why not? Simile and metaphor is just something we have been using for a long time. If you know what a simile or metaphor means than they can support your claim or thesis correctly.