To me, Google falls squarely in the disruptive and hard category. I mean no disrespect to Zuckerburg, but there's a reason Google was founded by two Stanford PhD students and not a bunch of bored undergrads.
This is a case where I think, just like Blanks states, the government's responsibility to counteract market forces for the common good plays a role. We should be tripling our research grant budgets for hard science. I feel like every week I'm hearing of an MIT PhD student making major breakthroughs in nanotube battery capacity or thorium reactor tech, but these aren't valuable investments for private VCs because the returns will not be quick and will not be as outrageous as a site that can go live tomorrow with the virality of the Ebola virus.
But that's just the way the cookie crumbles, ie, the market forces at work. I don't think it makes sense on a society level to be investing as much as we are in social ventures, and I hope we do find a way, public or private, to shift some of that investment back into solid tech. Wildcard prediction: biotech is the next big boom.