HTTP gets a QUERY method so complex searches can stop pretending to be POST

"Idempotent" may be jargon, but the term performs an important job in HTTP as a hall pass that gives reverse proxies and gateways the go-ahead to cache complex query responses and automatically retry failed requests. HTTP has long allowed automatic retries for idempotent methods, but complex queries are often sent using POST, which intermediaries cannot safely assume is retryable. Developers have worked around that limitation for decades.