As a parent, I felt a little defensive a couple of times while reading this. At the same time, I have to agree with 99% of what it says.
We have loads of extremely competent teachers. We have a great number of exceptional teachers. And we have some who could perhaps do better in another profession. In the context of the first two groups, I am 100% on board with the crux of this article. In the context of the few teachers who may be in the wrong profession? It really cannot apply.