Chart of the Day: Has Facebook Usage Collapsed?

I don’t know if I really believe this, but Facebook usage has plummeted in the past year according to a report in the Guardian:
According to the analysis, Facebook has more users than it did a year ago but they’re spending less time on the site and they’re engaging less with what they see. If this is true, it explains Mark Zuckerberg’s sudden epiphany that Facebook should deemphasize news feeds and pay more attention to privacy. Or, in any case, that it should say that it’s doing those things.