What a stupid comparison. Facebook launched from nothing; Google+ launched from the world's largest web company with the world's largest web and mobile audience.
Also, what a horrible article. To quote "according to data released on Tuesday by comScore. ... comScore noted in a presentation. ... according to comScore. ... comScore data show. ... the data show". Brilliant writing.
But it's an important statistic if you are looking for data about how quickly large companies can take a slice of an established market if they have a decent product. How quickly? - well - compare how long it took a startup like Facebook to do it to Myspace to Google.
It's still useful.
I take it, however, that you see it as stupid because of the implication that by mentioning the comparison, the article contains an implicature of "Google is doing better than facebook". When of course - it's not there semantically at all. What's more, that sort of implicature seems to be cancelled by the article directly stating that the statistic does not imply success.
It's just funny how people run with their own interpretations of a text. (I'm a bit aspie... can you tell?)
The original comparison still isn't entirely useful in that context. It's as useful as saying a car going 85mph will get to 90mph faster than a car at rest. Google+ came out at 85mph, Facebook started in neutral while parked in a private garage.
A more useful comparison would be how quickly Microsoft took away market share from Sony with the X-Box. Or the Zune vs the iPod. Or Android vs the iPhone... etc.