This works especially well in a situation like a networking event or large party where it is unlikely that attendees will know everyone else.
1) Instant connection - we both know {party_host}
2) You learn a detail about them (occupation, hobby, hometown)
3) They learn a detail about you
4) You've told someone why you're there, so then you won't feel like everyone's questioning your presence
5) You've got a starting point for talking to more people (introduce this person to someone else you know, and/or they'll do likewise)
This scares the shit out of the socially awkward or those the article is referring to. When entering a situation where I know almost no one, I always try to comfort myself by repeating things like "not everyone is looking at you" and "you are just like everyone else here".
However often times I take your advice and seek out other seemingly alone people and you're right, they're usually easy to spot .. if you're looking.