I confess I haven't read Steve's book (and probably should), but in the context of this post that flow-chart is misleading if it doesn't accurately represent his position.
I think it feels "misleading" because there is no time scale attached to it and maybe the word "Scalable Startup" should be changed. Building a scalable startup is all about the things you highlight... getting to problem/solution fit, then product/market fit... Key is getting there with low burn.
Once you have product/market fit, you have the semblance of a business. You transition towards growth from there.
I agree and hadn't really noticed the "Hire managers" text till now... Then again Steve is painting a picture for any type of business from a web startup to biotech.
My interpretation of this process for a Web startup is getting to transition using just the founders (plus advisors).
The idea is that you don't move beyond the 1st phase until you've thoroughly proved that your business model will scale. At that point, you DO want to hire managers, and grow your team. You've spent a lot of energy up till that point ensuring that your business formula will work, and it makes sense to take advantage of that by growing quickly.
It is different than the stereotypical valley mindset because the dotcom companies scaled before they knew that they had found a real problem, created the right solution, and sorted out a business model that could scale with more manpower behind it.
Once you have product/market fit, you have the semblance of a business. You transition towards growth from there.