This was the beginning of the delegation to the President of the authority.

Congress continued to delegate portions of its constitutional tariff authority to the President over the decades...done through legislation.

Now...if the USSC wants to begin writing its own laws rather than its actual Constitutional power...you may be correct.

It was the democrat party that wanted Roosevelt to have the power. It has taken over 80 years, with the rise of DJT, for this action to bite them in the ass. Prior to DJT, tariff's were just another bit of window dressing for the uniparty.