Pet peeve:
> N^2 scaling: if every fed has to talk to every other fed to exchange messages, the number of connections will scale exponentially
No. That's quadratic growth, which is a fairly mild form of polynomial growth, which is much much much slower than exponential growth.
k k^2 2^k
1 1 1
10 100 1024
100 1e4 1e30
In fairness here, when it comes to large distributed networks, this type of scaling is generally unacceptable.
But yes i agree its really sloppy for them to say exponential. I'd actually call it linear since what matters (mostly) is how many connections each node has to do, not the total number of connections in the system.
Nonetheless imagine if email worked by making a connection to every computer in the world to check if they had mail for you. It would obviously not work.