Yay!  I learned a new word!  Rather, two words, which when strung together make “technological determinism”.  As danah boyd points out (emphasis mine):

That said, the categorical term that we use to label a particular site or genre of social media does NOT determine practice. The intentions of the designers do NOT determine practice. The demand of the company does NOT determine practice. In science and technology studies (STS), we have a term for this foolish worldview – it’s called “technological determinism” and calling someone a “technological determinist” is an insult.

In short, Facebook said they aren’t the kind of site where people make friends with people they’ve never met in real life.  But, that doesn’t make it so.  What really matters is how Facebook’s users perceive their own presence on the site, and how they use it.