If I want to give a friend money, I can hand them cash, but I have to be in the same room as them. I can transfer that cash in other ways, but I need to trust the middlemen. I can also use a bank to send them money, but I have to know their details, which are sensitive information. I can use one of the plethora of money-transfer apps, but that involves putting my money under someone else’s direct control (someone who may go insolvent by the end of the year).
Or, if I have them on keybase (or any number of platforms, ideally) I can now just send it with a simple text message.
Additionally, what if I really appreciate something you said on HN, or twitter; or you made a really valuable contribution to one of my projects on GH? If you have your keybase proof on there, I can send you my appreciation in a matter of seconds. Imagine trying to do that using cash, PayPal, etc.
Despite the fact that until now, crypto has had far more overhead than cash and credit transactions, this and successor programs may have the potential to make transfers far more convenient.