Not understanding story is one of the biggest reasons that a pantsed book can look terrible to a developmental editor or other writers or a publisher. You throw everything in but the kitchen sink, including a 20-page scene that sounded cool, but fizzles out at some point.
Not having a story is like being out in the middle of the desert (having had way too much experience with the desert part!). It’s flat. There’s miles and miles of miles and miles. Maybe there’s a cactus here and there, or an oil barrel someone’s dumped. You wander over, have a look, but there’s nothing guiding you generally.
Story is like being a road. On either side, you have curbs, or at least the edge of the asphalt and those bumpy things to tell you if you stray off the road. You can still turn down that coolly named Aqua Ter (sounds like an underwater station) to see what’s there or check out what the heck the Stonewall Jackson Memorial is (not much, by the way).
You always have a direction, even if you aren’t sure where it’s going or ends up yet.
When you don’t have that direction, the story can turn into a mess and make you all that outlining advice be a siren’s call from across the sea.
But story is also a difficult concept to understand, and worse, it’s easy think you know what it is and have no idea once you make first contact. I read just about every craft book out there and thought I understood story. I did two novels, but during critiques of the second book, and other writers’ books, I realized how little I knew.
I’d like to say there was a craft book that could be read with a definition that gives you the lightbulb. But it’s a surprisingly complex aspect of writing. I think it’s something you have to come to your own understanding about.
So try taking a book that has been published, preferably a best seller, and read it cover to cover. Enjoy it. Don’t nitpick the sentences for flaws. If you want a book recommendation, try Michael Connelly’s The Lincoln Lawyer. He’s a pantser, and he talks about the writing of the book at the end, so you get an extra surprise there.
Then go back to the first chapter and reread it.
After that, go to an online critique group and read the first chapters of those writers and mentally compare it to what you read in Michael Connelly’s book. It’s not about having the inciting incident (a term that comes out of outlining) or a plot point (another term out of outlining).
It’s that you are going somewhere, even though you don’t know where.
Bonus tip: Type the first thousand words of Michael Connelly’s book. This is amazing way to learn something new about craft.