I agree you cannot recall the clear intent of the text of the document or the founders’ intent. An objective reading of their works would reveal their vision for this Republic does not include executive branch agencies creating law.
Administrative rule-making at the federal level began in the mid-19th century in response to criticisms that federal agencies were making decisions on an inconsistent, ad hoc basis, and often letting patronage and favoritism determine the outcome. You claim that administrative rule-making as a reform against such practices is contrary to the founders’ intent. On what specific documents and reasoning do you base that assertion?