Facebook broke through. We could have easily had a world with dozens of major social networks, each catering to a different subset of the world and consumer groups. Facebook, though, was able to gain nearly universal acceptance -- outside of countries where it is explicitly banned. There was no guarantee one company would take that prize. In fact it was more likely that we'd have Reddit, MySpace, TikTok, etc all catering to different audiences with no one platform that basically everyone at least has an account for.