The question I would ask is: once you have the ability to run code and store data on the network itself (which Cloudflare effectively is), why do you need an origin at all?
It can work for simple apps but there's a long way to go before any serious enterprise system will be hosted entirely on a FaaS system like Workers.
You're right for some use cases though.
At the point that CF replaces the origin, it is the origin.
The confusion in your query is the idea that "origin" is a rigid, fixed concept rather than flexible.