But could he do enough better [than hiring business advisors] to make up for probably a 15+ year delay in starting the business (due to time spent in college and postgraduate work PLUS the debt incurred in schooling)?

Edit: thanks autocorrect.

Depends. There have been exceptions you can point to, but many small businesses fail because the owner doesn't spend enough time in the office. "Joe Electric" works when "Joe" and one assistant is the extent of the business, but "Joe" - if he is in a good location - will soon have more business than he can accept at which time it is temping to expand, and then the MBA skills are needed or Joe's poor handling of the office work ends up killing the company.

If Joe was good at business he could keep 200 electricians busy with jobs that pay about as much as they would earn on their own, and no need for them to do all the book work in the office, and ultimately Joe makes more money.