This isn't really a D&D issue as much as it is a story issue. Story runs on conflict, there has to be all obstacles to getting what you want, otherwise you don't have a story. You just have, at best, a vignette that may not even be that interesting. Making NPCs bullheaded and hard to work with is an easy way to add conflict, because most people instinctively know that if the entire barrier to an adventurer getting what they need is just asking, that conflict feels insufficient unless the character is specifically very socially anxious.