That’s what a teacher is supposed to be, frankly.
Most of mine growing up were that, with varying levels of success.
Unfortunately, when teaching left the church/local municipalities, and became a national effort, the ‘standards’ went down, as well as the professionalism and morality of the teachers.
Additionally, it’s also a function of increased numbers - more teachers = more idiots as teachers.
I think it has more to do with, as you said, wresting control of education away from the local community, and also the demonization of Christianity. It has been a shock to me that secular persons of Jewish descent have been so prominent in their lawsuits against Christian expression in schools, given the experiences I had with Jewish/Christian benevolent co-existence in our school.