Obviously, they are a big problem, but they're not the only problem. It is received wisdom among doctors that increasing the number of doctors causes medical costs to go up, and it is generally also the position of the state.

The doctors are simply wrong; the state is correct from a pernicious point of view.

Because the state is responsible for buying so much of the total supply of medical care, they generally view things from the perspective of "how much are we spending on the category 'medical care'?", rather than the perspective of how much any given treatment costs.

Increasing the number of doctors lowers the cost of all treatments and is unambiguously good.

However, it does raise the total amount of medical spending, which, in the eyes of the state, is bad.