Put it in context, is it ever acceptable to have all your activity publicly logged? Keybase isn’t forward secure, so so disclosure of your keys later leads to complete availability of your cleartext.
IMhO, Keybase is adequate to protect against spying from ISPs, Ad agencies, journalists, etc but doesn't offer resistance against a formidable foe like a state actor, but then neither does most of the devices on which Signal is run.
I'd love to hear more as it doesn't match my experience. Among the oh-so-many IM apps I use, Keybase is my favorite as it's transparently cross platform, isn't tied to a phone [number], and the usability is good IMO.