And here we provincials thought Congress was supposed to make law.
Giving unelected bureaucrats the power to write law is designed to destroy the most basic tenet of a constitutional republic - that only elected representatives may write law.
The elected representative writes law and if the people are unhappy with the law, they can vote in new representation to write law they want.
The unaccountable bureaucrat writing law flips this concept on its head. With bureaucrats writing law, the people have no way to remove a bureaucrat writing bad law. This gives enormous power to grow government and create an unaccountable central government.
The unelected bureaucracy writing law is the soviet socialist model of governance. Unaccountable bureaucrats controlling the villages, towns, cities and regional areas of a state by writing arbitrary decrees is the primary trait of any totalitarian dictatorship.
And you're right - agencies illegally writing law is another gift from FDR the Marxist.