No. Social onboarding is a way of leveraging real world webs of trust to strengthen the Nostr network.
I am just a dumb fool crazy enough to put ideas on paper and put a bit of broken code on the web to maybe solve for it.
My open source code is a reference client. The first of hopefully many “social onboarding clients” to come. Also, hopefully, it will evolve into a library (social onboarding wizard) that other (not dedicated) clients can implement.
So no. Social onboarding is not centralized. Just a good idea for Nostr.
It’s all in the article. Read it.