> Also, as the OP noted, this setup can support up to 4 Mac devices because each Mac must be connected to every other Mac!! All the more reason for Apple to invest in something like QSFP.

This isn’t any different with QSFP unless you’re suggesting that one adds a 200GbE switch to the mix, which:

* Adds thousands of dollars of cost,

* Adds 150W or more of power usage and the accompanying loud fan noise that comes with that,

* And perhaps most importantly adds measurable latency to a networking stack that is already higher latency than the RDMA approach used by the TB5 setup in the OP.