"The common wisdom these days is that social-media platforms like Facebook and Twitter are playing a key role in popular uprisings like the one going on in Egypt.

"Facebook and Twitter, this story goes, allow millions of people to communicate and organize themselves, and they thus trigger revolutions and make them much more effective.

"But that's bunk, says Hani Sabra, an analyst who covers the Middle East and Africa for the Eurasia Group.