Those aren’t Flask components. They just work well with Flask. And Jinja, SQLAlchemy, and Alembic just happen to be the largest and best of them.

Many of these independent components pale in comparison to their Django counterparts in glaring ways—they are often a pain to use, with some pretty questionable internal code choices. They remain used because they are often the only choice out there, even though their implementations are inferior to Django’s.

I say this as someone who has used Flask for over 5 years, as well as nearly 5 years of Django.

They are flask components cause they work well with flask and work bad with django.

Parts that I mentioned are (or were when I compared) light years ahead (especially sqlalchemy).

I totally agree on SQLAlchemy. It’s very good. As is Alembic.

I feel like most using Flask would consider “Flask components” to be equivalent to Flask extensions—e.g., Flask-SQLAlchemy vs SQLAlchemy proper. Maybe it’s a pedantic nitpick, but I’ve never heard anyone refer to SQLAlchemy as a Flask component in 5+ years, hence my comment about the distinction. But yes, many of the Flask-compatible Python packages you mentioned are quite a joy to use.