There are too many micro-specialties and not enough crossover. Imagine if once you were a frontend dev you would have to go back to school for 2 years full time to be legally allowed to do ui design of a button even though there is a lot of crossover and knowledge sharing between roles.
This definitely causes shortages and issues when the demand naturally rises and falls for various Healthcare disciplines.
I'm not saying formal education isn't important but there could be a much more fluid crossover between various allied health disciplines than their is currently.
Maybe more transition programs or seeing individual billing codes for Medicare attached to education modules
If it weren't profitable to have large numbers of staff per doctor, there wouldn't be large numbers of staff per doctor.
Now make an argument that the current arrangement is more optimal than the one we might end up with if there were more doctors.
The real problem is the unaccountable bureaucratic management, which are neither physicians nor nurses, and the numbers of which continue to expand (sucking up financial resources) while physicians and nurses workload increases and pay continues to decrease in real terms.