Which makes sense, of course, since Keybase is a funded startup that needs to capture value... and, well, centralized file sharing is a more straightforward solution, too.
The file system thing seems really cool and useful. I'm a fan of Keybase and will recommend this to people with whom I need to share sensitive data.
It'd be interesting to hear the Keybase people talk openly about how they see their role as both infrastructure providers for an open web of trust, and an economic entity that requires for its survival some degree of lock-in and centralization.
As an infrastructure provider, they open source the client software and design it to trust the server as little as possible. They also endeavor to document the behavior of the server so that, in theory, you could build your own Keybase-compatible server.
As an economic entity, they're positioned to tackle the issues that open source projects usually face, like support, development resources, UI design resources, and "where do you put all of this encrypted data" by getting their most needy users (mostly businesses) to pay them.
https://ipfs.io