The "trap" of MongoDB was more due to the exaggerated marketing around its features and data reliability out-of-the-box. Since Postgres already has plenty of mindshare, it wouldn't need to resort to such tactics, so it could describe its features with "giant red exclamation points" describing the exact pitfalls and extent of the use cases. So I'd be very much in favor of its developers prioritizing specific clustering solutions.
Documenting is one part, but that doesn't really answer the "simple setup" requirement if people have to read a lot.
Ideally, even someone who doesn't read the documents would be gently and intuitively guided toward the right solution and away from costly mistakes. Easier said than done, but let's try to get as close as we can.
