I do think the impact good teachers have is relatively minor, except for the part where a good teacher isn't a bad teacher, and the damage a bad teacher can do

I do think the impact good teachers have is relatively minor, except for the part where a good teacher isn't a bad teacher, and the damage a bad teacher can do is enormous. A young inexperienced teacher is almost certainly getting into the career because they want to help kids. They may become a bad teacher, the bitter sort of teacher, after many years of seeing little but negative outcomes. At that point, they become part of the problem and realistically the only way to correct this is to wait until they quit. Incidentally, high wages are more likely to keep bad bitter teachers in jobs they hate longer, while young optimistic teachers require less fiscal motivation.