The article at part reads like the vague "get off my lawn" ramblings of a bitter elderly man. Good luck attracting top young talent with this attitude.
Another important point is that most startups aren't a good place to stay long term, simply because (duh!) most of them do not succeed. Curious, isn't it?
Statistically, over a 3-4 year period, your startup is 90%+ likely to fail. Why would the best and the brightest stay in a failing project? The captain may be expected to sink with the ship (he often doesn't, and especially his first officers don't), but when you realize that this isn't your company, your "stock" isn't going to be worth a nickel since any meager sale profit will go to the series A investors, and if you don't start sending out resume you're going to be fired in a couple of months - why again are you expected to stay?
Also, many of the best engineers I've known have periods where they changed jobs, and then periods where they stayed at the same job for 2-3+ years. That just makes sense. If you can get hired anywhere, and since you can't really gauge the merit of a company from a few hours of visiting it pre-hire, you're likely to shop around and try to find a place that you like.
Ultimately, as you correctly pointed out, if an employee is truly happy in his current position, s/he will not leave. And it's your job as employer is to keep the employees you want happy and productive in your company (what other task does a manager have, really?). How anyone can ignore this simple fact is beyond my grasp.