That I agree with. Well, I agree as much as I can, because I haven't written a book, but I have written a few web apps (and have started a company). Let's say for the sake of discussion they're reasonably similar, even if perhaps they aren't.
Yes, creating technology is a lot easier than it used to be. Marketing is probably easier as well. But I don't believe whatsoever that building a web app is the same as building a billion dollar business. There are a few examples of business which got lucky, fine, but having started a startup myself, I can say (in line with many others, pg included) that running a company is so much different -- and so much more difficult -- than just hacking up a web app.
Steering a company to massive success requires so many difficult decisions and skills that often have nothing to do with your core competencies (unless you're one of those mythical creatures who can 'do it all'), that you need the support of at least one other person who is either A) better at it than you are, or B) can work together with you to figure out how. Those mythical creatures are the 11% in the pie chart, but the other 89% of us need more manpower behind the wheel.
Whipping up a Rails app in a weekend is not the same as running a company.