Typically the secret data you're interested in is specific to a particular user. Session cookies, for example. (Not saying this is universally true, this is jus

Typically the secret data you're interested in is specific to a particular user. Session cookies, for example. (Not saying this is universally true, this is just the scenario I think is on most people's minds.) If the traffic is common to everyone, the NSA could just browse to the site.