Alright, for fetching data,queryset should be enough.
But posting/patching/removing uses the serializers's queryset.
Also, sinceRelationshipView supports multiple creation/removing, we should validate all the data in one go (normally, DRF validates each serializer independently, resulting to o(n) queries).

Perhaps overwritingvalidate will work for this type of serializers given the above differences. But it is better if it's in the library rather than having it in each app's source (mostly the exact same code).

I am a bit confused by your explanation. Could you post a code snippet how you would picture an improvement?