The best argument I see in all that text is that it can leave you with substandard work. The rest of it is a lot of corollaries to the idea that doing speculative work is not a good deal for a designer.
I think the idea in this guide is that substandard work is preferred to burning time or cash on professional design work. You aren't even sure you have a viable business. You should absolutely minimize time to iterate and cash spent in this scenario.
I'm all for supporting designers, doing business locally, and the importance of design. Unfortunately, sometimes people need things in the context of scare resources that don't permit the ideal choice.
Once there is a business...find a good designer and develop a great relationship.
