According to the article, "Giants Tighten Grip on Internet Economy", a small handful of tech giants, such as Facebook, Amazon, Google, Apple, Microsoft control the internet economy and generate record earnings. What are key factors for them to dominate the internet economy? Why do think other companies do not share a significant portion of revenues with them? Briefly discuss.

Source: Don Clark and Robert McMillan, "Giants Tighten Grip on Internet Economy", Nov. 06, 2015, the Wall Street Journal (Eastern Edition).