The problem with that is that it can be difficult to know what you need, and it may be impossible to simulate in any practical sense. Like, sure, I can stand up a pair of test systems and fabricate every scenario I can possibly imagine, but my employer does want me to do other things this month. And what happens when one of the systems involves a third party?
Really, the need is to be able to provision access after the relationship is established. It's weird that you need a completely new secret to change access. Imagine if this were Linux and in order to access a directory you had to provision a new user to do it? How narrow do you really think user security access would be in practical terms then?