Sure there is: Article I, Section 1

All legislative Powers herein granted shall be vested in a Congress of the United States, which shall consist of a Senate and House of Representatives.

Anything short of "all" contradicts that.

Now you need to find somewhere that says "Oh, btw.. we didn't mean 'All' but really 'some' because Congress might give some legislative powers to other branches."

That doesn't seen like a reasonable interpretation. The power is vested in Congress, so they can use it. Delegating authority to an agent is not exactly novel and it definitely doesn't somehow mean that Congress no longer has that power.

So if I give you complete authority to design and implement a new exommerce system, it means you must do it single-handedly with no delegation to anyone?

This “anything not expressly allowed must be forbidden” is the exact opposite of how US law works.

> This “anything not expressly allowed must be forbidden” is the exact opposite of how US law works.

With regards to the Constitution, the 10th Amendment would disagree.