Some of the best sales people I worked with, indeed some of the executives, who each year sold tens of millions of dollars worth of very large computer systems to top corporations, had never graduated from high school. Most had never graduated with any kind of degree. Some had general arts degrees and a few had MBAs.

 I have never encountered a lawyer, doctor or engineer that had not completed post graduate university studies in their specific field before going on to earn their practicums and designation as professionals.

There is nothing remotely comparable that is required to prepare people for a sales career. You are 'officially' a sales person the moment you sell something. It's a 'job', not a 'profession'.