Sqlplus and sqlcl are widely used for batch access to the database, in a service process running somewhere in the background.
They already have an option to fail after the first login attempt : -L
Otherwise, after a bad password, you would hang forever if you did not provide any input.
But also for other failures, an input is requested. E.g. when you accidentally have substitutions who are not yet resolved.
These kinds of hangs are difficult to find, because you expect some database lock or slowness instead.
On fora, you will find a solution in redirecting the input from a file.
But it would be better if there is an command line option to put sqlplus or sqlcl in batch mode, that makes it fail when sqlplus is going to read from stdin.