In the older version of the proposal, -> was identical to ->> except -> returned NULL on malformed JSON (while ->> raised an error). Both -> and ->> would automatically convert a JSON-encoded SQL string '"like this"' into an SQL string 'like this'. This is not how the -> operator behaves in Postgres and MySQL, and my examples were simply trying to point out that incompatibility.
https://dev.mysql.com/doc/refman/5.7/en/json-search-function...