The text you quoted explains why you wouldn’t want to create a single service account for all customers. It’s a security decision, which yes adds overhead.
I'll note that the overhead is only on the provider side; from the customer's perspective it's all the same. In contrast, OpenID Connect puts overhead onto the customer (in addition to the provider) which I find unfortunate since I want to provide a good experience.
I'll note that the overhead is only on the provider side; from the customer's perspective it's all the same. In contrast, OpenID Connect puts overhead onto the customer (in addition to the provider) which I find unfortunate since I want to provide a good experience.