The point I was trying to make is that for many people being able to copy back and forth between a local folder and a mounted directory is no different than what they do everyday at work with networked folders. Many people are just moving the occasional document, picture, or folder. For those people Keybase could definitely work as a Dropbox replacement. I don't think the typical Dropbox user is expecting their ZSH profile to be omnipresent on their multiple computers/laptops/tablets.
You may be misunderstanding intent.
Also, to be clear, you could use the mounted files directly, but you just have to be aware that if you lose connectivity you may run into issues. If I was traveling somewhere and I'd like to work on a document in transit then I would recommend copying that to another folder on your local machine first.
"I copy files out of it to get around that it's not good at what I'm trying to use it for" is not a super winning argument, either.
KBFS is fine. I use it for stuff like SSH keys. It's fine. It's not Dropbox and it isn't substitutable and it doesn't need capes.