> If Zoom was to one day shut Keybase down, your private key is now gone. Otherwise for security over convenience, if you store it on your own computer you're more likely to lose it.

I'm not so sure about this. Each of my devices absolutely has a key stored on it that is offline capable. Loss of keybase servers would matter but not the extent that you're claiming, from what I can tell. https://book.keybase.io/security#your-private-keys-are-only-...