I coached one year of girl's youth softball. That was enough. I loved the kids but 1/3 of the parents were either frustrated ex-or non-athletes trying to live through the kid. I never had much trouble personally because we had a new team and we were simply not as talented as most of the other teams in our division. Once I told the parents that, two pulled their kids and went looking for better diamonds. I doubt either kid made a high school roster later.
But the other parents were cool with honesty and we could deal with questions like grownups do. However, there are coaches that think yelling is the same thing as teaching. I played for one of the best hisgh school football teams in the nation and one reason was that the coaches could teach and only yelled when it made sense. And they never rode the officials, even with a bad call.
Overall I think most high school football coaches are better than in my day. My only complaint generally is that some are so "scheme" focused, they come up short on addressing fundamentals.
So, Parents: Shut up and watch the game. If you think you can do better, get a degree and a coaching job.... or get a striped shirt and try reffing a few games.