It’s a more generalized solution, that’s for sure, but it feels like it adds a lot of complexity and indirection in the process. The “flow of code execution” is all around with the callbacks, and it took me a few back and forths to actually understand how it was working.

Now, if you have a large system and many more of these “type keys”, by all means, this is an appropriate solution. But in the example of user type / creation, I beg to differ: the earlier example is much simpler to understand and reason about.