Those guys are talking out of their buttholes.
I have written books. Other than the lower back pain caused from typing at the kitchen table, I can't really complain about the creation process. Sure, there are difficult choices and hard moments where I struggle to express myself. But it's nothing like going through labor and delivery. Squeezing another lifeform out of your body--a lifeform that you are terrified will turn out to have the wrong number of limbs and your uncle's nose--is an exercise in fear, discomfort and a strange hysterical bliss. If you want to draw parallels to writing, you can, but I pretty much guarantee that with all the fluids going on, childbirth is way more disgusting.
But people who feel that their books and their stories are like their children are totally right. Have you ever watched the mother of an only-child? She flutters around, offering stimulating activities and unwanted hugs. She counts each serving of vegetables that crosses her sweetling's gums (and stays down). She studies the pages of every parenting advice magazine and acts upon the gems she finds. When her little love-apple strays out of her sight, she panics and runs in circles, calling her baby at the top of her frantic lungs.
The mother with three children, however, functions completely differently. She sweeps through the room without concern for choking hazards, concentrating her prowess on critical moments, like imminent leaps from the upstairs landing. Kids are encouraged to read to each other, and if lunch is peanut-butter-jelly sandwiches for the fourth meal in a row, well, at least they are eating. When her children are out of sight, she sighs with relief and tosses back a shot of Jack, followed by two cups of coffee.
The simile is simple. Writers are like parents. The writer with one or two projects to nurture dotes all her energies upon those projects. Each story is given every ounce of attention, its submission process planned and watched with obsessive care. When the rejections come, they strike her core. And more often than not, the writer goes through round after round of revisions, polishing within an inch of her life.
But once that writer has put a handful of pieces out in the world, she begins to be more cautious with her energies. If a story trips, it will get up again and try another venue. If a piece has gone through two drafts and a good round of proofreading, it's ready to send out. And if a friend disagrees with the phrasing of a sentence, the writer shrugs it off. She has the confidence to tell the quirks of character from the truly awkward moments.
I have one daughter, and we keep a chalkboard in our kitchen to track how many servings of fruits and vegetables each of us eats. She had five today. I have five stories this month that I'm sending out for submission or critique, and about a dozen in retirement from last year. And you know what? They probably didn't eat a single vegetable today. But I have faith they'll grow big and strong anyway.