Signing up for facebook and telling people what you are doing prevents you from keeping this info private. But writing letters does the same thing, and I don't

Signing up for facebook and telling people what you are doing prevents you from keeping this info private. But writing letters does the same thing, and I don't see people complaining about pen and paper. It's a shame that FB privacy settings are confusing (and ever changing), but aside from that, why blame the communication medium for what you choose to say (or not say) with it.