@peach414144 - You are correct- medical education today is very different from 30+ years ago. The basic structure is still there in learning how the body works. There is such a lot of new data coming out continuously. In the old days doctors/students would buy one major book in Internal Medicine, Pediatrics, Surgery etc. it doesn’t work well like that now. Many illnesses change and as you mentioned illnesses are now studied on a molecular level.
Within each specialty are many subspecialties nowadays etc. The more complicated or unusual illness the less likely it is for your primary care doctor to know much about it. However, a doctor should know when to find help from others! Signs and symptoms help, but many are not specific. Unfortunately, we have to know ourselves when our doctor is not enough. A good primary care doctor can be very helpful in managing referrals etc. and interpreting test results for example if you are seeing specialists elsewhere.