Additionally, incorporating DRF [or any other 3rd party lib] into core would lock them into Django's release cycle.
As for built-in REST/API features, Django provides `JsonResponse` already, so the main piece lacking is de/serialisers.
The built in serializer framework is well suited to generating fixtures, and _can_ be bent to serialising your data for APIs, but does not provide any solution for validating input.
Our existing input validation solution - Forms - is not so good at handling complex or deeply nested data structures.
However, in recent years tools, like pydantic and marshmallow, have begun filling this space.
One place we could help everyone is by providing a JSON request-body parsing utility.