well if you and your friend (singular, just one other person) has lots of content and you don't need to communicate with others, then by all mean, connect your PC together and have your own "Internet" and live happily ever after.
But can this go from wireless router to wireless router... And on an on.... Even to people you don't know...
yes. try lookup router in wiki.
but i guess they all in the same subnet, so the router act more like a bridge. it's like a big wireless LAN
Yes, I'm also not quite sure how this is just an intranet rather than an internet. It's between two networked devices, but can't connect to the global wider internet, which is what most people need. The intranet I believe only allows transfers between whatever computers are connected.
I didn't follow the link, but I expect this may be a mesh network. The idea is to use the wifi on a peer-to-peer basis, essentially creating an intranet. But presumably some points in the network have internet access, and can make it available as a resource for everyone on the local mesh network.
I tried out an app that now does that for general use by non-technical people, but uninstalled it because it was using up the battery too quickly.