Enforcement of relational integrity on bulk load should be optional -- you trust the data, right? But also, if you want relational integrity, then you have to

Enforcement of relational integrity on bulk load should be optional -- you trust the data, right? But also, if you want relational integrity, then you have to check it somewhere. Lastly, this isn't about DML or bulk load but about query expressivity. You could easily have FOREIGN KEY constraints where the RDBMS is also instructed not to enforce relational integrity, either on bulk load or at all, and documenting the FK in the schema is still massively useful.