Ao3 (Archive of Our Own) exists for people who want to read stories. People come to Lemmy (and sites like it) to interact.

One suggestion would be to make interactive stories. Have someone post a chapter with a poll or ask what a character or characters should do next. Whichever numbers or arguments win the author over determine, or help determine where the story goes. Communities like AskOuija (not sure if I spelt that correctly) do a similar thing on a much smaller scale.

Writing is kind of a big, busy task. If someone were only expected to write a chapter or a short chapter at a time and let people vote on the stories they care about, someone whose story got no traction would have no obligation to continue. Or they could try again with another story. You could even offer writing prompts (or just cross-post them from a community dedicated to them).