Every time I hear a comment alike parent's, it makes me think how many times a day I actually read a comment in the same fashion, but about something I actually know nothing about.
With credit to the original poster, they might be complaining about the fact that Django is a monolithic framework and you can't really use Django code without spinning up the i/o portion. Which is legitimate criticism, but frankly if that's what you need then you shouldn't be using Django.
Without calling setup, you cannot import anything that touches Django models, like constants defined in a file that transitively imports a Django model.
In practice, this means that any script that depends indirectly on Django code will incur a lengthy startup cost (from having to call setup()), and will fail to run if there's no database connection, even if the script itself doesn't need the db.
Django _does_ have a "setup" function. You can't import and use Django database connections outside of a running application without it.
Flask also has a "run" method and does no i/o without it.