I can believe that was a motivation, but it's quite possible to have a licensing system for doctors and at the same time keep costs in check. For example European countries typically have much lower healthcare costs than the U.S. (even after taking into account tax money spent on the sector), despite still stringent licensing requirements for doctors. The U.S.'s system is a particularly bad case of letting the inmates run the asylum, so to speak, both on the occupational licensing side, and on the drug side (the other half of the cost equation, where e.g. Medicare is statutorily prohibited from negotiating prices with pharmaceutical companies).