The Truth is: There are many, many coaches in travel ball who are hopelessly incompetent, but for some reason have control of those teams year after year. The parents of the better players simply move their kids to different teams. The parents of the average or weaker players generally don't know the difference. High school is a different story. Outside of selling your house, you're pretty much stuck with the high school coach who is generally more into the politics of the team than anything else. It's almost comical watching some of these guys and gals trying to manage a game. They're just lost. Once in a blue moon a kid gets lucky and plays for a high school coach with a clue. But not very often.
As for trying to tell parents they can't talk to each other? I can't stop laughing. That rule is a sure sign that the coach is an absolute goof. If he were worth a darn, the parents wouldn't be grumbling amongst themselves. All parents grumble from time to time, but when they do it to the point where the coach is implementing ridiculous rules like that one, then it's time the coach just gave up the reins to someone else. Most of these guys have a kid on the team who might not get a uniform if someone else were coaching. That's the main problem.
My kids are now playing for a club that has a rule against the parents saying anything to their kids during a practice or a game. They can't go over to the bench and ask if they're feeling all right, want to go to McDonald's after the game... If the rule is violated, then the kid has to ride the bench for the next game. The parents also can't talk to the coaches about their kids' playing time. The kids have to do it. I didn't know about these rules when I signed them up. I don't generally say anything to my kids during practices or games, but I don't like to be told I can't. I rarely say anything to the coaches, but it's stupid that I can't. My kids will play elsewhere next year for sure and this season hasn't even started. I coach my daughter's 14U softball team and I always talk to the parents during the game and after the game. I tell them why I'm doing what I'm doing or did what I did. It helps that I played the game for a lot of years and know what I'm doing. If one of the kids isn't getting a ton of playing time, I don't wait for the parent to come to me, I go to the parent and tell him/her/both exactly what their daughter needs to do to get more time.
Paranoia in coaches is a sure sign of insecurity/incompetence. Here's a tip: Get good at what you do and you won't have to worry about people complaining.