Why do you insist the words “all legislative power” are equivocal? Why do you not consider agencies go beyond “rule-making” and are creating law?
I guess I am done asking you questions, as you’re unwilling or unable to answer the previous ones.
Maybe a closer reading of the history and context of the writing of the Constitution would help you understand.
Good luck.
Congress exercises its legislative power when it establishes administrative agencies, enacts statutes to regulate them, and when provides appropriations and other funds for their operation. Your argument comes down to insisting that Congress’s legislative power does not extend to requiring administrative agencies to adopt substantive rules. Nothing in the Constitution says that and you are unable to point to any original contemporaneous sources to that effect.