Is that Chris Dixon...
... the Ghanaian footballer, or Chris Dixon the champion yachtsman. (These were the top two results when I looked up the name). In other words, he might be a friend of yours, but he's a long way from being so famous that anyone could get away without putting a one-clause bio after his name.
On the article, a fair point, but only up to a point: photo-sharing is not fundamental to using the Internet in the way a browser or search engine is.
Put it this way: if you own the one-and-only browser, it doesn't matter how many content discovery systems there are, you can dictate which one is used. If you own the one-and-only content discovery system, it doesn't matter how many photo sharing applications there are, you can dictate which one people find. But if you own the dominant photo sharing application? Well, someone else can start a new one and compete with you. Instagram managed this against Flickr (or beneath them).