Everyone seems to be reacting to the "viral marketing" framing of it, when basically this is just a graph theory problem. Reading this, it appears that finding

Everyone seems to be reacting to the "viral marketing" framing of it, when basically this is just a graph theory problem. Reading this, it appears that finding seed sets is an old problem. Normally people focus on finding minimum-size seed sets, but here they're just focusing on small ones. However, they don't appear to have actually proven any upper bounds on the sizes of the seed sets found this way; they've just observed that empirically it's small. Which is still useful.