Plots that are profitable to write abound, but plots that any specific person likes may well be quite thin on the ground.
I think the key here is that authors don’t feel the same attachment to submitted plot ideas as submitters do (or the same level of confidence in their profitability), and thus would view writing them as a service done for the submitter. Writing is hard work, and most people want to be compensated if they’re going to do a lot of work to someone else’s specifications. In scenarios where they’re paid for their services, writers often do write others’ plots; consider e.g. video game novelizations, franchises like Nancy Drew or Animorphs, and celebrity memoirs. (There are also non-monetized contexts like e.g. fanfiction exchanges, in which participants write a story to someone else’s request and in turn are gifted a story tailored to their own.)
I wouldn’t describe LLMs’ abilities as wonderful, but IME they do quite serviceable pastiche of popular styles I like; if your idea is e.g. a hard-boiled detective story, MilSF, etc., I would expect an LLM to be perfectly capable of rendering it into tolerable form.
Plots that are profitable to write abound, but plots that any specific person likes may well be quite thin on the ground.
I think the key here is that authors don’t feel the same attachment to submitted plot ideas as submitters do (or the same level of confidence in their profitability), and thus would view writing them as a service done for the submitter. Writing is hard work, and most people want to be compensated if they’re going to do a lot of work to someone else’s specifications. In scenarios where they’re paid for their services, writers often do write others’ plots; consider e.g. video game novelizations, franchises like Nancy Drew or Animorphs, and celebrity memoirs. (There are also non-monetized contexts like e.g. fanfiction exchanges, in which participants write a story to someone else’s request and in turn are gifted a story tailored to their own.)
I wouldn’t describe LLMs’ abilities as wonderful, but IME they do quite serviceable pastiche of popular styles I like; if your idea is e.g. a hard-boiled detective story, MilSF, etc., I would expect an LLM to be perfectly capable of rendering it into tolerable form.