I don't buy that reason, because that inconsistency can be easily prevented with good schema hygiene (either ON DELETE NO ACTION or ON DELETE CASCADE). The prob

I don't buy that reason, because that inconsistency can be easily prevented with good schema hygiene (either ON DELETE NO ACTION or ON DELETE CASCADE). The problem is rather that in order to maintain consistent data relations, delete operations must be carefully designed and that part of the functional design is usually skipped because it's perceived as not important. Which is more or less what the GP says as well, deletes are not implemented because doing it properly requires proper design.