The reason is that Keybase wasn’t designed to be hosted by anyone except the Keybase team. There’s no documentation on how to run the backend, and only a 9-page long string of Github projects to go on. Even if someone were to figure it out, the system is probably designed to be a globally scalable service, not a small clone being hosted for the benefit of a few. The design and expense of two such systems are vastly different, and not always compatible.
While the Keybase source code may be open, the infrastructure is closed.
I’ve called these types of networks “commons networks” — like IPFS — and have also stated that I want to create constellation providers not cloud providers.
Serverless is the biggest threat to open source, as it is majorly closed and proprietary infrastructure.
Also: the joke about not mentioning Web3. Web3 design principles are about commons networks where many can participate and tries to solve hard problems around bad actors.