"Google owns search, but Facebook owns you. Which is more valuable for selling advertising?"

I disagree with this frame and this his implicit answer.

Facebook's advertising model is sort of inherently adversarial. Their ads have to distract you to be successful. That means there's always a tension between user experience of the product and the revenue stream.

Google's meaningful innovation was capturing your intent, so that it can give you relevant ads when you're actually looking something, often to buy. All the social stuff is in service of making that relevance part better, but it's an inherently more constructive model of advertising.

I think it also works a lot better, and is much harder to replicate than Facebook's.