I think comparing bitcoin to facebook is kind of like comparing apples to oranges. Bitcoin is a P2P "currency" while Facebook is a social network. The uses of the two platforms are just too different
I don't think they were comparing the two sites in that way. They meant how popular it got, once you heard about it you had to go make a facebook account, same as bitcoin, once you hear about it you have to own one.
Bitcoin is still in its early stages. 9 out of 10 people I ask (probably more like 99 out of 100) if they have heard about bitcoin and most say no. I have met very few people IRL that has never seen it on CNN or heard of it online. The majority of people that use it are the ones online on their computers, not the average person that works a 9-5.