Social media has been a total failure at turning people out in the streets - all it does is de-aggregate people into increasingly tiny cloistered micro-interest-based Facebook pages or twitter-tweets. The massive protests of 2001-2005 were all organized by traditional street posters, hand bills and phone-banking plus the now-sadly-defunct Indymedia sites - plus ordinary websites and e-mail lists having a large part too.
What has there been since the "Twitter Revolution" and Facebook replacing the older methods? Well, the sadly disorganized, tiny and fizzled "Occupy".
The difference is that all of the earlier successful organizing tools - including the older internet-based ones - notably Indymedia - whose demise was tragic, were broadcasters of ideas. Web pages and the Indymedia news site were accessible to everyone via an easy to remember URL on a poster or handbill or word-of-mouth. E-mail lists, phone solicitation, hand bills and posters - or browsing local news headlines on Indymedia were things that commanded attention - requiring no initiating interest or action on the part of the recipient. These actions are a megaphone for which the speaking is done from the proper (narrow) end.
In stark contrast, social media is "narrowcasting". To even be aware that organizing efforts exist at all, I have to know (how???) the specific facebook page or twitter hashtag, and have an account with these services - and if I know if these Facebook pages, then I'm already a member of the self-preaching choir! Using social media for organizing It is like shouting into a megaphone from the wrong end!
And make no mistake - the billionaire Ayn-Randite tech capitalist interests designed Facebook and Twitter to produce exactly this effect of dispersing and atomizing all effective mass organizing against their capitalist interests. And the truly tragic thing is that those who are think that Facebook and Twitter is the best thing for organizing since sliced bread are completely clueless that they are the very victims of the capitalist's social-consent engineering process!