pg_isready is "ncat -zv $host 5432" for systems which don't have ncat installed.
Pretty sure this is also an incorrect, or at least incomplete statement. pg_isready uses the PostgreSQL wire protocol to make a better determination as to readiness than ncat does. People are just complaining that it doesn’t go further than it does. They see “user” and “database” and misinterpret why those options exist.
We've had this discussion before: people see the --dbname and --username options, then quite reasonably think "ah, those options must mean you can test whether a specific database and/or role can connect; otherwise, why the heck would you put them in the --help output?"
Bottom line: the purpose of --dbname is to specify a database name; the purpose of --username is to specify a username. Having them in the --help output misleads the user.
