Because med schools job is to teach you the basics of being a doctor. That's more than enough to be getting on with.
They also don't teach you billing/coding, politics of medicine, practice laws, malpractice cases, or any of a number of things that physicians in the real world deal with because they're too busy teaching you the fundamentals of medicine.
MIdlevels haven't overrun primary care so you can stop with the hysterics. We're doing just fine.