From my point of view, controlling the canonical namespace is a form of soft power in the ecosystem. Since as the post says, the actual files are hosted on GitHub, the cost of the extra load on their infrastructure is real but probably not material to a company of their size -- as I understand it, it's more like running a DNS service than a file host.
So it _seems_ (the word I used above as well) from my perspective that they’re giving up a bunch of soft power for little gain, but it's very possible that I'm either wrong about the value of the soft power, or wrong about the cost of running the infra.
I published a terraform provider when the registry in beta while working at a startup. They do some “value ads” like code signing and such, but you’re right - it can functionally be replaced by the GitHub release page.
So it _seems_ (the word I used above as well) from my perspective that they’re giving up a bunch of soft power for little gain, but it's very possible that I'm either wrong about the value of the soft power, or wrong about the cost of running the infra.