I won't disagree when it comes to authentication and admin interface, but test suites (pytest), an ORM (SQLAlchemy), and migrations (Alembic) are not very hard

I won't disagree when it comes to authentication and admin interface, but test suites (pytest), an ORM (SQLAlchemy), and migrations (Alembic) are not very hard to set up. Furthermore, you can use them in other non-frameworked projects. Of course, it's hard to build something like an authentication/admin interface framework without there being some standardized ORM/migration system, so the argument is more or less moot.