The sentence within the doc should not be considered in isolation.

The "Logger" object is *not* ignoring the message (in accordance with the documentation and your expectation), but the "Handler" is, see https://docs.python.org/3.8/library/logging.html#logging.Handler.setLevel and here: https://docs.python.org/3/howto/logging.html: "The default level is WARNING, which means that only events of this level and above will be tracked, unless the logging package is configured to do otherwise."

Logging is quite complicated, and reading the API reference is not the best starting point, as is noted at the top of the page and links provided.