While the reasoning holds generally, that specific example is wrong.
The type the author presents is not the “User Profile” but a “User Profile Load Resource” (or something in those terms).
When you actually design interfaces you discover that there are way more states to keep in mind when implementing asynchronous loading.
1. There’s an initial state, where fetching has not happened yet
2. There may be initial cached (stale or not) data
3. Once loaded the data could be revalidated / refreshed
So the assumption that you either are loading XOR have data XOR have an error does not hold. You could have data, an error from the last revalidation, and be loading (revalidating).
When you actually design interfaces you discover that there are way more states to keep in mind when implementing asynchronous loading.
1. There’s an initial state, where fetching has not happened yet
2. There may be initial cached (stale or not) data
3. Once loaded the data could be revalidated / refreshed
So the assumption that you either are loading XOR have data XOR have an error does not hold. You could have data, an error from the last revalidation, and be loading (revalidating).