Ok actually we thought again about it and I think we want to keep these. They are the only way to put permissions on the container level. I.e. the permission is not a django object in DjangoLDP, it's just a virtual representation of all objects of the same type. I think the best way to decide who can add a user in the user container is the model level permissions. So we probably want to keep these.
But we still need more testing to make sure it is working as it should.