[notahacker]

I've seen some pretty stupid analogies in my time, but the idea that logging onto a web service other people use to broadcast stuff they want to broadcast to the world is "violating their personal space" in a manner akin to covering their lawn in trash is going to take some beating.

[loup-vaillant]

Revealing something about you reveals something about everyone around you too. Facebook happens to have the means to correlate all this information, and use it to its advantage.

It's not just looking at what others broadcast. Facebook keeps track of your likes, your navigation patterns, and let others access that. So not only do they know what your friend broadcast, they know who is watching, when, how frequently.

Finally, there's the social pressure. I have been a victim 2 years back: forced to subscribed to Facebook because my orchestra were using it to communicate loads of important information (I have since deleted that account). By watching your friend's broadcast on Facebook, you contribute to, or at least fail to counter, that social pressure.

That said, I reckon you're probably a victim that social pressure as well. I won't throw the first stone.

[avoidit]

I have seen some pretty stupid replies in my time, but a reply espousing the idea that someone who doesn't get the actual analogy will have a pet list of "pretty stupid analogies" is going to take some beating.