There are market externalities to two parties agreeing not to compete. Unlikely to be significant in larger markets with many independent service providers, but

There are market externalities to two parties agreeing not to compete. Unlikely to be significant in larger markets with many independent service providers, but definitely of potential concern in smaller markets--e.g. rural dentists. The externalities could swing positive or negative--non-competes may be required to maximize the number of rural dentists--but still something to keep in mind either way.