The reason monopolies are illegal is precisely because they force people to be completely dependent on a third party.

Is a farmer "a failure who shouldn't have a business" if some asshole buys up every single railroad, port, and truck in the country he lives in?

No, but if he makes himself for example completely dependent on Monsanto, he shouldn't have a business, because he's in practice an employee with all the financial responsibilities of a business and none of the benefits of having a business. And none of the benefits of being an employee either.

If your business model is to make yourself completely dependent on a single third party, then you shouldn't have a business.