I would say everything is influenced by that.
I agree with you regarding the sights and trigger. I think the single greatest detriment to long-range accuracy is thinking that a long, slow "surprise break" is beneficial. One the sights are on - they're on - it's time to commit to the trigger in short order, otherwise you'll wind up mentally talking yourself out of a good shot.
Of course besides the technique, people fail to build up their knowledge base learning how their gun hits (and how they hit with their gun - a separate issue) at different ranges and with different types of ammo. This can cause all kinds of frustration as well.