Plenty of writers work collaboratively, fyi. Even fiction authors like my mother routinely deal with multiple drafts and edits from multiple editors who review and suggest changes, from peer authors to professional editors contracted by the publishing house. And non-fiction authors routinely collaborate, too. I personally know some consequential non-fiction books where another author ghost wrote troublesome sections, not taking credit except in private.

And this ignores the collaborative writing many authors do to pay the bills: technical writing at large corporations, like bank manuals and such, or academic writing at universities. While consistency and standards are enforced, nobody's arguing that everyone else should really indent paragraphs their way, because that's the best way.