I’ve found croc to be more reliable than MW in across different network architectures — croc has worked in places where MW has not. I’m not sure why.

If you have IPv6, it’s easy. In IPv4 land… Good luck.

File transfer isn't an OS level problem. There are already a million utilities that let you get a file from computer A to computer B if they are reachable over IP. Connecting the computers in a secure way is the hard part, hence the need for all the workarounds.

Fair, though I think a large part of why this has always been more difficult than it should be is the fundamental design of TCP and IP. The former encodes notions of “roaming client” and “durable server” in ways incompatible with devices that periodically want to assume either role, and the latter (at least IPv4) encourages network segmentation in such a way that reachability and discoverability are harder than people might think.

The centralized powers that be definitely deserve a share of the blame to be sure, but some of it is architectural.

It was easy, via Airdrop, but the CCP doesn’t like people being able to share files in a decentralized manner in groups, and Apple ceases to exist as we know it if they don’t do whatever the CCP wants, so it was nerfed.