Are they really? I remember what the web was like in 1993. It was a hobby, there were no big players, and all the major corporate attention was focused on WebTV, virtual reality, RISC architectures, 3D computer graphics, and other "big ideas". Much like people think of mobile, Google X, hardware startups, the sharing economy, etc. today.

There are a number of technologies now that remind me a lot of what the web was in 1993. BitCoin. 3D printing. Common Crawl. And there are enabling technologies like smartphones and cloud computing that aren't being used to their fullest potential. I suspect that the same conditions that led to Marc's rise still exist in other areas, we just won't know what those areas are until a whole new ecosystem has risen.