KT17, I think the setters should solve and go over each other's puzzles with a fine tooth comb, to make sure no errors or ambiguities appear.
PS I agree with your father but only partly. Writers should never be the only ones to proof-read their stuff, but they surely have a responsibility to ensure that what is typeset is what they said and meant. The editor, sub, copy-editor might not realise how crucial a certain word, phrase or semi-colon is!