At a conference recently, an industry guru made an impassioned argument that Google should immediately buy Pinterest, the photo-pinning social site that has taken the world by storm.

The argument was persuasive.

Here, in a nutshell, are the guru's key points:

Google sucks at social and will always suck at social. Despite its humongous user numbers, the guru says, Google + is a bomb. It's a bomb because, once again, Google is playing catch-up and because Google just doesn't know how to build good social products. Wayne Gretsky's famous secret to success in hockey was to skate to where the puck is going, not where it is, and Google is skating to where the puck is. Facebook has the puck, the guru says, and there's no way Google will catch up if it keeps chasing Facebook. Google needs to skate to where the puck is going.