Only watched a bit of it, but it seems like a headache to maintain. As it's completely decentralized how do you manage what service can access what service. Imagine if you know one service that can access 100 other services is compromised and you then have to remove it's public keys everywhere.
Having a centralized solution like Keycloak is much better. You have a centralized point of controlling what services can access what services. You have a single place where you need to protect the private key. You can much more easily remove access to a compromised service.