If we're really thinking about it (let's do that. Yawn, stretch.), I guess one might liken fiction writing to the laying out of the contents of your mind, experience and imagination on the tablecloth, and then obscuring it from sight by applying layers of narrative, characterisation or style.
Ideally this adding of layers generalises it, allowing it to transcend the writer’s individual experience, making it palatable and accessible and, all being well, moving it from the realm of the confessional into the realm of art. Some writers layer thickly, others less so. The thinnest veils come inevitably with biography or memoir, when the writer themself is the story and there is no extra narrative or characterisation added as a disguise. This is known as letting it all hang out*.
Ideally this adding of layers generalises it, allowing it to transcend the writer’s individual experience, making it palatable and accessible and, all being well, moving it from the realm of the confessional into the realm of art. Some writers layer thickly, others less so. The thinnest veils come inevitably with biography or memoir, when the writer themself is the story and there is no extra narrative or characterisation added as a disguise. This is known as letting it all hang out*.