There seems to be a natural arc to the process we keep reading about: Get investors & users with your cool design. Burn cash. Have an IPO. Flail as you try to m

There seems to be a natural arc to the process we keep reading about: Get investors & users with your cool design. Burn cash. Have an IPO. Flail as you try to monetize. But, they're at least succeeding at something that Google couldn't do if their life depended on it, which is make a social thing people want to use. What I don't get is why Google doesn't just swoop in either at the early stage or at flailing-and-monetization stage, buy them and stick them in their back pocket.