From a coaching perspective, it is inherit in the beast. You must have a plan in dealing with this issue. Our plan is to have a Parent's Meeting at the beginning of each year. The veteran parents can almost recite word for word what is going to be said. We also make a handout (7 pages) that outlines our philosophy, talks about being the parents of athletic children, outlines our "Qualities of a Baseball Knight" while also outline the process we would ask that they use should they find the need to talk to us. Since we are in such a small community, I already know potential HM Parents and I make special attempts to communicate with them what we expect before their child makes the team. For instance, I might see a parent at a basketball game and they might want me to know every stat that Johnny has since 4th grade. I'll be courteous but tell them that I really don't care. I also make sure that they know that, while I enjoy talking to them, we won't have any conversation such as this during the year. Well, I could go on and on.
What we do is right for us and has worked well for us for a long time. However, it might not be right for you. There isn't a one size fits all answer for this issue. Believe me, I've seen this issue in EXTREME FORMS and yet, we've had success. JMHO!