I can't remember all the times I've heard a parent tell me I should "use flash cards" or "not give homework" or "don't use flash cards" or "give more homework." Parents haven't been teaching high school for years and can't generally discern the good teaching from the bad, too often basing their judgments on fleeting or non-germane criteria.
"Is he passionate about teaching classes"? "Is the flow of his class natural"? "Does he maintain discipline at all times?" "Does he have a complete knowledge of his subject area?"
How is a student (with no actual classroom experience except for sitting in the back trying to see that girl's boobs without being noticed) supposed to answer these questions? How is the parent supposed to do any better?
Parental input should only go so far. For a parent to have "massive and sustained input" is simply a bad idea.
The Athens Banner Herald editorial, however, seems to like this idea a lot:
Frankly, what's missing in the tug of war between legislators and teachers over school funding versus classroom accountability, except for a passing mention in Senate Bill 521, are the voices of the people who are most qualified to speak out on the quality, or lack thereof, of the state's public schools and teachers. Any meaningful assessment of schools and teachers must include massive and sustained input from parents. (emphasis mine)