I think Mark is right, that chronic switching is a leading indicator of selfishness. But the days when employees are kept around while they fill out their pensions are gone. Most employers are signaling that it's every man for himself.
If you founded a startup, then quit abruptly at the first sign of real challenges, and now you're trying to found another startup - how would prospective investors look at you? (Even if the former investors aren't already suing you, which is entirely possible).
On the other hand, if you are an early startup hire, and you stick with what is obviously one of the vast majority of failed startups, so you get to be fired when they reduce their headcount to what they consider the best engineer (you, alas, happen to be considered the 2nd best) - how is an employer going to look at you, compared to someone who left two months before?
That's right - you were fired, and he quit. There's obviously something wrong with you.
Comparing employees to founders isn't only completely bogus - it also shows why the entire article is false, trying to explain why employees need to behave like founders while they are a very, very different thing.