I've been using it a bit, and it's really nice. Yarn (and the npm command line tool) already provide nice methods to install packages from arbitrary locations, including git repos; this provides a nice mechanism for publishing to git repos. It's a super simple solution, but then, it's not really a hard problem.
Distributed systems. Mirrors. Tools that are agnostic about sources for packages.
There's no reason that we must have a single, centralised package repository for a language and the dominant tool chain for that language relying on it by default.
nix (pkg manager). Can give you an insane amount of control of how your project builds, especially if you use nixos, but with great power comes great responsibility XD.