You're factually wrong about social sites running on vanilla technology. I bummed more cache misses out of tight paths, and invented more data structures in on

You're factually wrong about social sites running on vanilla technology. I bummed more cache misses out of tight paths, and invented more data structures in one year working on Facebook's search backend than I did in any of my nine years working on VMware's virtual machine monitor. Being a mediocre guitarist is probably easier than being a mediocre violinist; and writing a Facebook clone that works for a few million users is easier than writing a web search engine that supports comparable traffic. But when you are trying to expand the boundaries of what is possible, everything is hard, even things that seem easy when tried in their simplest form.