Three experts; three different views; that's what you get when the three look at the impact of the substantial rise in the number of mobile devices accessing the network. All these devices send traffic across the network and much if it hits servers and causes storage transactions. Ethernet set up as a fabric can help here. But …
that was interesting, thanks
re: "In the past, all traffic flowed up and down a tree-like network, metaphorically North-South from edge to core and back again."
No, that was only true in 802.1d networks. Cabletron (later Enterasys) had SecureFAST, which allowed traffic to traverse the LAN without regard to the spanning tree topology and allowed for multiple active connections between switches.
If they ported it to current generation hardware, it would put most, if not all, LAN topologies to shame.