Maybe I'm overreading it, but RDA does specify "Profession or Occupation" as a type of term appropriate for distinguishing one person from another. To me, this implies an expectation, or at least an option, that the term will be categorized as indicating a profession or occupation. MARC authorities accommodate that by providing the 374 field where the RDA category is expressed in the tag value. I can imagine other ways a term could be categorized, including a term added only to an authorized access point; and but MARC is what we use. I agree that RDA does not require this kind of categorization; but it does encourage us to make it possble. If RDA did not intend to distinguish different qualifying information by categories, then I'm not sure why the 3XX "RDA fields" were added to the authority format.
What is missing from RDA itself is any instruction to use controlled vocabularies to express the attributes of persons. That comes from PCC. I'm all for using controlled vocabularies; but I can also see a case for using the 374 to categorize an uncontrolled term which appears in a 100 $c.