You needed a GitHub account and a KeyBase account. So people created as many accounts as their bot networks were capable of, and tried to get the crypto.
Thankfully KeyBase changed the requirements to include "account must be X weeks old".
Edited to add: I'm not sure if there's a way to prevent bots these days. Feels to me that we're lucky (more?) economic systems haven't been bled dry by bot networks.
I miss the promise of KeyBase. It felt like a real digital identity, but for whatever reasons it wasn't good enough to succeed.