[EdiX]

Step 1.d.i.a:

If the system has implemented the utility as a regular built-in or as a shell function, it shall be invoked at this point in the path search.

[aidenn0]

1.d.i only happens if the search in PATH is successful.

I think the logic behind this was to ensure that as shells add more built-ins scripts that depend on an executable failing when not in the path won't break.