When I started using Rest Framework as I had more need for API endpoints than HTML pages I realized the Serializer API was way easier and more intuitive and pulled more weight. Then I began using Pydantic and its API design does pretty much the same except for the rendering part.

I think the rendering aspect in the Forms API has always been a PITA and the validation aspects always left something to be desired. Rendering and validation/serialization should be decoupled IMO, and in that sense the Forms API fails.

Sometimes I wish for the Django admin to be reimplemented in FastAPI/SqlAlchemy as a more modern approach to the same problems.