In the same way being an hobbyist programmer will never give you the same skill set than a CS degree. It's highly unlikely you are ever going to study extensively algorithm, os and databases design, compilation or declarative and functional programming all by yourself because objectively it's not something you need to get the job done. Nevertheless, this knowledge becomes really useful as soon as you start designing complex system.
Doing an MBA (or an MSc for what it's worth, MBA cult is mostly anglo-saxon) is exactly the same thing. You will study a broad range of subjects and business areas and see different theories on them.
Don't misunderstand me, practical knowledge is invaluable and running your own company gives you a good understanding of your area. It's just than MBA will give you a broader if less practical view.
