FAITHFUL followers of Twitter believe that Jack Dorsey, one of the social network’s founders, is the only person capable of turning around the struggling firm. Mr Dorsey (pictured, during a recent Old Testament beard experiment) returned as its boss last year, taking over from Dick Costolo, who had led the company during a chaotic round of executive departures and strategic changes. True believers hope Mr Dorsey will be a reincarnation of the late Steve Jobs, who returned from exile to restore Apple to greatness.

So far, however, Mr Dorsey has yet to perform miracles. On February 10th Twitter reported lacklustre earnings for the first full quarter that he has been back in charge. It now has 320m monthly users, no more than it had in the previous quarter, and it is unlikely to turn a profit until 2019.

When Twitter went public in 2013, some believed it could become larger than Facebook, an older rival. Mr Costolo promised to build the “largest daily audience in the world”. Its prospects looked bright. Unlike Facebook, which began as a service on desktop computers, Twitter has always been popular on mobile devices, so it did not have to cope with a difficult transition.

However, it has become clear that Twitter will never become the giant it was supposed to be. The pace at which it is adding users has slowed far sooner than it did at Facebook (see chart). Mark Zuckerberg’s outfit, which now has 1.6 billion monthly users, has grown swiftly by buying potential competitors such as Instagram, a photo-sharing site. One sign of Twitter’s ill health is that its number of users in America has stayed flat, at around 70m, for a full year, suggesting that it is approaching a ceiling in the world’s most important advertising market.