but there's clearly a necessity that those services be provided in some form or function, and the 538 members of Congress are clearly not up to the task of managing all of that on their own, especially once you consider that most of those agencies are far larger than Congress itself.
That's precisely the point; those who wrote the Constitution and those today who believe similarly do not believe many of those things are the job of the federal government, and for those things which are, Congress should be the only body in government with the power to pass laws, as they are elected which gives the people some direct way to keep them accountable and not appointed/hired. This delegation of powers is a large part of how the government has gone about expanding it's powers and scope.
The other problem is reinterpretation and redefining words and meanings of the Constitution to achieve political/ideological goals rather than using the means provided in the document to alter it. Maybe there's some civil right like the 2nd Amendment you disagree with (not accusing, I don't know nor care, this is just for discussion) and maybe this achieves your short-term goal(s), but it weakens all the other civil rights most people, including yourself, value, and renders them vulnerable to the same methods and strategies to effectively nullify/rewrite/abolish them. A case of "be careful what you wish for, you just might get it!" for those