I think the author misses the major argument, which is "I have to make rent". Most startups never get to the point of making a profit.
This is why now isn't generally a good time to start a company (unless you are able to raise substantial investment). Now is a great time to get a job at a funded startup, save money, learn skills, make friends - once the bubble pops you'd have the basic ingredients to start your own thing (and - possibly - without a job anyway, so have nothing to lose)
This works well assuming you're disciplined about it. When I graduated, I knew I wanted to start my own startup, but I planned on bootstrapping and needed money. I worked two years exactly, living cheaply and saving as much as I could.
My job was comfortable and I really loved it. It would have been very easy to stay. The advice to start "now" is really a reminder that if your answer is always "tomorrow," you'll never get started.
I'm not sure discipline has any place here at all. If there aren't 10 moments every day in your corporate job when you wish you were in a startup and could do things your way, then you probably wouldn't enjoy being in a startup anyway.
I would say that falls under "I have debt." Perhaps better phrased is "I can't afford to bootstrap."
At the very least, it limits your options in terms of what kind of startup path you take. If you can't afford to bootstrap, then your only options are either working around a fulltime gig or trying to raise money out the door (from investors or friends/family or loan).
This is why now isn't generally a good time to start a company (unless you are able to raise substantial investment). Now is a great time to get a job at a funded startup, save money, learn skills, make friends - once the bubble pops you'd have the basic ingredients to start your own thing (and - possibly - without a job anyway, so have nothing to lose)