without a strong foundation it will be difficult to build a start up and an MBA is a good foundation for someone to start a company, maybe there are some people who without an MBA are able to make their company grow big, but can everyone do that? there is nothing wrong with starting a business directly without an MBA, but the struggle required is very heavy, even management knowledge is mandatory to master. My senior kept telling me not to be hasty in starting something, first strengthen the foundation and mentally.
But without a strong foundation or a strong knowledge, I don't think it's easy for one to handle an MBA course. Another requirement would be money and we know that not many are fortunate to have that both, which is why they will just start their business immediately with only minimal knowledge and money on their head and hand. They can still be successful if they get lucky but if they fail, they can still learn from it and try again.
I too believe that not all who have an MBA course are successful on their business. Sometimes knowledge is not enough but other traits are necessary too. Skills for example and then passion for the thing that interests us.