Writer's Fallout Shelter

Given some of the things I've written and read over the years, I don't really find the expression all that bizarre.

There's a stage of learning the art of storytelling where this:

<i>Making stuff up has never been unacceptable; quite the contrary.</i>

takes precedence and people think if they've never been to space, or Winesburg, OH, that it's perfectly acceptable to play fast and loose with the details without doing any research. The worst non-published story I have read started with a comet striking the earth. Reading it, it was painfully obvious that the writer had no understanding of astronomy and had not bothered to do the research necessary to make the story believable. He was actually quite offended when I suggested that he take the time to do some research because "it was fiction and he could write whatever he wanted."

All that said, one of my writing partners claims the axiom is inaccurate. She says it shouldn't be "write what you know" but "write what you want to understand."

What do you guys think of her adaption?