Making a long distance complex network may be expensive, but to connect directly a few computers one can use 25 Gb/s Ethernet at a reasonable price.

Last time when I checked, dual-port 25 Gb/s NICs were not much more expensive than dual-port 10 Gb/s NICs.

If you have a few computers with no more than a few meters distance between them, you can put a dual-port 25 Gb/s card in each and connect them directly with direct attach copper cables, in a daisy chain or in a ring, without an expensive switch.

No, of course I'm not going to if I choose thunderbolt :). But in many cases it's fine because SSDs aren't nearly as noisy as HDDs, so the NAS can just sit under your desk.

For 40+ GbE or fibre I agree they are expensive, but at least you get full performance out of your system. SSDs aren't cheap these days either...