> To do this for 1.5M users only when Facebook's user-base runs into billions Well, put like that, it sounds just like they did it as a planned A/B test strate

> To do this for 1.5M users only when Facebook's user-base runs into billions Well, put like that, it sounds just like they did it as a planned A/B test strategy (like they do to trial other features) — and, personally, I believe this to be the case. Deploying such code/functionality is hardly an accident/bug.