https://www.huffingtonpost.com/allen-frances/we-have-too-many-speciali_b_9040898.html points out

The most powerful departments in any medical school became the ones that attract the most research dollars and produce the most clinical revenue by doing highly reimbursed medical and surgical procedures. Primary care teaching and practice has always been deeply devalued by medical centers because it does neither.

Primary care is best at the unglamorous and financially unrewarding task of taking good care of patients. Primary care is worst at promoting institutional prestige and profit

In 1961, almost half of US physicians were general practitioners; by 2014 the fraction had declined to one third