Funny you should say that:
https://httpwg.org/http-extensions/draft-ietf-httpbis-safe-m...
https://httpwg.org/http-extensions/draft-ietf-httpbis-safe-m...
Not idempotent: POST
idempotent/not safe: PUT (body matters), DELETE (no body)
safe: QUERY (body matters)/GET (no body)
That’s why QUERY is needed. POST is not a good substitute.
"POST" has come to imply a "write" operation, and mixing up the the reads and writes of a system leads to cognitive dissonance.