The inference I got from the article is that the author felt the MBA *used* to provide job security.
And nothing could be further from the truth.
The notion of true job security is a relic of the 1980s and before. Not to sound too cliche, but we live in a very different world. There's really no such thing as job security in virtually any career now.
If you work in a for-profit business, you are always one bad fiscal year (or even calendar quarter) away from losing your job - from the entry level grunt all the way up to the CEO. There was a recent study of CEO turnover, and how it has gone from 20 years (i.e. forever) before 1970s, to around 10 years in the 1980s/90s, to less than 5 years today.
If you have a technical position especially in software/hardware, the more experienced you are the more you are at risk of being replaced by the kid who just got out of their MS program (I totally understand why so many engineers want out after 5-10 years; it's hard to stay in the game when they can eventually replace you with some fresh grad who is cheaper and more up to date on the latest stuff - I mean, the world's most experienced FORTRAN or COBOL expert isn't exactly a hot commodity).
If you work in government, you are at the mercy of cutbacks.
If you have a union job, the union can't really help you if the company you work for needs to really scale back.
If you work as an attorney, you also risk getting axed if you happen to work in a practice that sees its billable hours dwindle with the economy.
We are simply not shielded from any economic cycle.
The sooner people can come to terms with the reality that there is no such thing as job security no matter what you do, the better you'll be able to ride out any cycle.
Having said that, there's a bright side to this. Because there's no job security and by extension no "life long career" anymore, our working lives are no longer linear. Linear is boring. We have the potential to reinvent ourselves every 10-15 years or so, which can be an amazing thing. It's certainly scary to start over, but once you've done it your first time it becomes easier to handle emotionally, mentally and financially the second, third or even fourth time. In prior generations, most people's life's work could be summed up as "I started as an XYZ at 22, then worked my way up until 65." You basically just did one thing (or maybe two). With this generation going forward, you can look back on your life at 80 and say you've lived many lives in that period - you've been an engineer, an entrepreneur, a preacher, a writer, and an elected official. That's really an amazing thing when you think about it. Even if you didn't necessarily succeed in all those roles or time periods, it was still a far more interesting legacy and contribution to the world at large than "I worked as XYZ at 22 and coasted until 65".
And an MBA can be valuable in that equation. Because it's a generalist degree, you can use it to open doors to different industries. No matter how specialized your industry experience is, you always have that generalist foundation and perspective. If anything, the learning experience in an MBA program de-mystifies business. It makes stuff like "how do I figure out how to price this thing I'm selling?" or "how do I set up a company?" or "how do I figure out whether this business makes financial sense" from something mysterious and nebulous, to something that is tangible and specific. A lot of people who don't have MBAs are scared of this - they are afraid to look at a balance sheet. They feel that marketing is some mysterious crystal ball gazing. They are intimidated by the jargon, the analysis, and the dynamics.
As such, an MBA really teaches you how to look at virtually any situation from a business context which can be invaluable. For example, if you ended up working at say, Microsoft for 10 years before getting laid off, the generalist foundation you have from your MBA program (even if it was an eternity ago) can give you the confidence to say, "you know what, I've always wanted to work in the wine business" and to figure out how to do that. It's not that the "credential" itself that will open the doors, but the education itself that will even make it possible in your own mind. Oftentimes, it's not that the doors are closed, but that we often don't give ourselves permission to say "I can do it". The experience and education of an MBA can help in again de-mystifying business - that "business is business no matter what the industry" and that what you are doing is simply applying that perspective to *specific* wrinkles on that concept.
So no, the credential or even the education itself can't give you job security, but it can be a great asset in helping you start over in another industry or even job function (or even if you decide to do something non-business related for say 10-15 years). And the ability to reinvent one's self is probably the most important thing (even more important than networking in my view) you can have. Because it's practically a guarantee that virtually every one of you will have at least 2-5 careers between now and 70 -- and oftentimes careers that have nothing to do with one another (and some of which may have nothing to do with business). And the timing or nature of "starting over" may not be of our choosing. We will get laid off maybe even multiple times. We will hit a plateau in our current career sooner than we think. Our jobs will become obsolete. Our industry may become obsolete. It part of the rhythm of life now. But it can be a blessing too because for every door that slams in your face, there are other doors that can open if you're willing to look beyond the hallway you're in and maybe across the street in the other building.