loubylou, with respect I think you are also missing JD's point. As professionals I am sure that if something is mandatory then we comply! But there is nothing wrong with healthy debate about the issue because for one thing that's how we learn.
As one who has been involved in training during my aviation career for quite a while now, I know that we learn more effectively when we understand why a procedure is necessary rather than just doing things by "rote".
So please let's have the statistics - how many altitude busts have occurred on departure because QNH has been incorrectly set?
As a humorous but valid aside I like the story of children asking mum why she always cut the end of the roast off before placing in the oven. She replied "That's the way my mother always did it!". They went and asked grandma who said "That's the way my mother always did it!". Fortunately, great grandma was still living so they visited the old folks home to ask her and she she said "Because my oven was too small for it to fit in!". I think the moral of the story is that just because we have been doing something a certain way for a while and it's become established is not a reason for asking some critical questions as to why we are doing it. In NLP it's called "Starting with the end in mind".