With all that money they've raised, it's puzzling why they don't take PR seriously. I guess they have a mentality of "where the fuck else are you gonna go, the node community is tightly coupled to our service"
Their lack of financial or other interests in the community directly explains their policies.
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.
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.