Whoa, edges are also objects (meaning nodes/vertices)?

Can you give me an example of why that is necessary or would be useful?

So if I have:

(N1) --E1--> (N2) ---E2---> (N3)
        ^            |
        |-----E3-----|

First is this an acceptable "graph" in BitShares? And who "owns" edge 3? The source "node" of edge 3 is edge 2. The source node of edge 2 is node 2. So does that mean that the owners of N2 control edges 2 and 3?

http://bytemaster.bitshares.org/article/2014/12/24/Introducing-BitShares-Object-Graph/