It's not "hacker nonsense". 37signals is generally fairly different in their opinions from most hackers (e.g., I strongly disagree with their opinion that Moore's law means web companies shouldn't wory about scalability: Gene Amdahl may beg to differ).
What Jason is saying is common business sense: don't sell something you haven't built. Build something as you're selling it, iterating on the product and adjusting to customer feedback. When the product gains traction, take external money (if needed and desired) to scale the business.
Facebook already had (measurable) traction _before_ they took VC funding.
This is not VC funding! This is seed capital... VCs hand out millions, not a couple hundred thousand. I believe in boot-strapping, and I boot-strapped my own start-up, but if these guys can get a small amount of money to work with, it is helpful.
What Jason is saying is common business sense: don't sell something you haven't built. Build something as you're selling it, iterating on the product and adjusting to customer feedback. When the product gains traction, take external money (if needed and desired) to scale the business.
Facebook already had (measurable) traction _before_ they took VC funding.