I pretty much agree with everything you've said but I think most of the worries are rendered harmless if keybase are clear and up front about the trade offs. If

I pretty much agree with everything you've said but I think most of the worries are rendered harmless if keybase are clear and up front about the trade offs. If you have a need for cast iron privacy and security, don't use them. If, on the other hand, you just want a semi-secure solution that prevents run of the mill third parties from intercepting reasonably benign day to day communication then maybe the risk is worth the convenience. You could also maintain a second keypair unconnected to keybase for things that need to be really secure and private. For me, the interest is solely with their approach to trust anchoring. I like that it simultaneously provides a place to post a brief bio, a public key and a way to tie the key holder to github and/or twitter accounts. I'm using that part of their offering now but I have no intention of ever giving them my private key.