The rub is that: so do terrible teachers.
It's inevitable in a world where bureaucrats take a top down approach to test taking and measurement that you end up with people who "teach the test". It sucks.
But, when left to their own devices, some teachers don't teach at all. Teachers follow the same distribution of personalities as any other occupation on this planet; some are good, some are bad, most are average. These standardized tests were an attempt at saying, "You MUST teach at least this well", with "well" being defined by factoids. So, on one hand you have a free-for-all, where great teachers influence and inspire, while poor teachers ruin lives. The other side is a middle ground where what is to be taught is quantified, and everyone gets a mediocre (at best) education.
What we need a hybrid system that allows good teachers to do what they want, while bad teachers are held accountable and forced to, at the least, teach the test.