[d2zo]

Perhaps, but you don't turn around and give the shampoo producer intimate details of your life. Instead, you probably forget that you have the sample and end up throwing it out 6 months later.

They're different businesses, I'm not sure that you're comparing apples to apples.

[rbarooah]

We don't know how many people sign up because someone said it was cool or invited them and then forget that they have a Facebook account.

It serves Facebook to publicize a giant number to make them appear unbeatable, but the numbers that count aren't about number of users - they are about usage.

I think it's a reasonable analogy.