I suppose it depends on how they're counting uniques, but I doubt it has much, if anything, to do with how many accounts there are on the site.
I just checked their users page (http://stackoverflow.com/users) and they 8003 pages of 35 accounts, which comes out to be "just" 280,105 accounts in the system, including people who just stop by once to ask or answer a random question (you don't need to create an account there, they create a cookie-based one for you when you do something on the site the first time).
They're pretty much definitely identifying uniques via some combination of cookies, IP addresses, and perhaps some other methods. I seriously doubt you bother to clear your old cookies before creating each new account on the system.
Besides, I got the impression that the article was referring to the entire network, including the StackEx sites, in its totals.
I'm a bit like you too, btw, in that I have more than one account there, but for a different purpose. I've created new accounts there before to ask what I think are really dumb questions. It's bad enough that the top voted question on my account right now is "Should I find a new career?" which I created during a particularly bad time at my last job. That question is probably the single biggest reason I never signed up for their Careers service, right after the fact that there's basically nothing there for Canada.
Do you mean that you didn't sign up for the Careers service because you felt you had revealed damaging information about yourself
That's a big part of it, yeah.
potentially still edit some of that revealing information
Not really. I think the questions existence is damaging enough. The only way to get rid of it is to delete it, but I'm an inclusionist, and the question is bound to help someone down the line. I'm sort of alright with its existence now, it's a part of my past that will always be there so I shouldn't be trying to hide it.
change the username associated with the question
It doesn't work like that. I sort of wish you could dissociate yourself from certain things on that site, but you can't. I'd have to create a whole new account.
In the end it doesn't matter. I just did a search for Canada jobs on Careers.SO and it only gave me 8 responses, four of which were American jobs located close to the border. Careers offers basically nothing to be, and certainly not enough to justify paying for it.
