Things like Airbnb don't exist without the Internet -- fundamentally they connect people who wouldn't have met any other way.
It's about building communities that didn't exist before. That's significant. The modality is the difference. People didn't have a reliable and simple and cheap and instant way to connect. Now they do.
Agreed. My point is that there are certain people that would likely be predisposed to share anyway. And although the internet has provided new opportunities for sharing, other types have occurred in different communities (village, folk, scientific, etc.) for ages.
Basically, new opportunities don't mean that people wouldn't have shared or weren't sharing in other ways.
It's about building communities that didn't exist before. That's significant. The modality is the difference. People didn't have a reliable and simple and cheap and instant way to connect. Now they do.