It is indeed simpler. It is also incomplete. But saying a complete PKI requires centralization is not accurate. I think you might like this article, the author solves a different, but similar problem towards the end but it gives some insight https://buffrr.dev/blog/are-we-self-sovereign-pki-yet/

Complexity is price. If the cost of self-sovereignty feels too high, you simply want to buy freedom back cheaply. Pay the cost or lose your soul.