I was curious so I just had a look with my (fake name) account and the option called "Allow others to see what content I've viewed in feed" was set at "No". I don't recall ever playing with that setting so this may be a recent change on their part to avoid the backlash.
Mine was also 'No', but then I visited the homepage (http://www.quora.com) and closed the notice there about the new Views feature... which toggled the setting to 'Yes', without any message to that effect.
So try viewing the homepage and then check the setting, or closing the fewture notification... it may then be 'Yes'.
