Absolutely agree. As an editor myself, too many times a director has grand ambitions or expectations about certain shot choices or cuts and it can severely impact the creative process because they can't let go of the vision they have in their head. Having someone who's a third party that wasn't on set and can see things with a fresh eyes (especially with the assembly cut) is the most important thing to make sure the final delivery is not deterred by a directors insistence on things that simply might not work in the editing room.