From my count, he has had 3-4 jobs in 3 years. Why would you want to hire someone who can't even stick with his own company?
So, this isn't a parable to apply to entrepreneurs in general. It only applies to quitters.
Figure out what you want to do on your own dime, prove it, and then you'll be marketable.
What's more, the design industry runs on freelancing. Consequently, direct-to-fulltime positions rarely open up for non-management positions, since most design firms have a cadre of long term contractors already waiting to make the jump. My wife was laid off from a design firm, and had 2 interviews in a year for full time positions. The rest of the time, she contracted. I had 3 interviews last week, and 2 this week and 3 more next week, with several companies in the wings.
At the same time, since it's a freelance industry, there are always people trying to farm out contract opportunities, which suggests that the author isn't interested in finding paying work, just in finding a paycheck.
Finally, even more than in software, you are your portfolio. It's really almost anyone cares about. If the author can't find >any< work, he should look there first.
Finally, I call bullshit on 'any good employee will leave'. It's a very design culture thing to think that professional relationships are inherently competitive rather than cooperative in nature.
The author of the book I quote is trying to elucidate the point that you should hire people who are better than you. Don't be afraid that they might leave. He drives that point home with the rule that anyone good will leave, so go ahead and hire 'em anyway.