Isn't the presentation talking about each host acting as a router? So any gateway only needs to know about the prefixes that are the next hop downstream, not ev

Isn't the presentation talking about each host acting as a router? So any gateway only needs to know about the prefixes that are the next hop downstream, not every single host. Maybe I have this wrong, but I think the idea here is talking more on layer 3, whereas you are imagining everything sharing the same layer 2 network?