Interesting reading this because this is essentially the principle behind https://socketcluster.io/ scalability; the sharding of channels across available brokers is pseudo-random. It uses a hash function for determinism but the distribution appears to be random and that was also the best way I could find to distribute load evenly between available nodes. It is key to its embarrassingly parallel design.

It's interesting to see it being done at the data centre level as well.

That's a different thing entirely, that assumes you already have a physical layer that allows any client to connect to any broker, this is about building that physical layer