I think it's a lot harder to pick a good business than you think. Many "micro" sized businesses have significant issues and avoiding them requires you to know all the right questions to ask.

If you are able to make the right pick and the size of the deal is something you're comfortable seeing go to zero, it may be a good learning experience.

However, you'll be learning to acquire and keep a business alive, not start a business through this. Some things may remain the same depending on the stage of the business but if you're looking for experience starting a business, I think starting on and failing will be better training (and free)