I think the confusion comes from that not everybody thinks of "passing data to the database layer" as an output, but only an input to the next layer. If you thi

I think the confusion comes from that not everybody thinks of "passing data to the database layer" as an output, but only an input to the next layer. If you think of this input as an output from the previous layer, then your advice makes perfect sense. But I don't think everyone thinks that way so it might help to clarify what "output" means in this context.