Ah this may be our disconnect. I was specifically talking about how the new companies needed to grow and reach users in order to scale. In cases of nearly of the large consumer platforms, they leveraged other platforms to do just this. And in pretty much all cases they were able to build on top of the other platforms for free. The core infrastructure, etc is definitely important — but rarely built on the backs of others especially for free. Amazon web services is a foundation for many companies now but they pay for it so the relationship is very different