The problem with your argument being the Constitution conveys supremacy to the federal government in many areas. So the idea of giving "90% of the power back to the states" suggests your lack of understanding that they never had that much power and never were intended to by the Founders.
No it doesn't. Being constitutional takes away a lot of the federal governments power and authority the government has now. There are a ton of new things going on now, under the control of the federal government, that the states should be taking care of 100%. Like education.
But politicians like to redefine things to make it sound as if the government has the constitutional authority to control something. Like that "general welfare" clause. That could be redefined to account for all sorts of things. The new definitions are worded to make them sound reasonable.
A good example of this is eminent domain, in the 5th Amendment. If you know the 5th, then you'll know it's ALL about the governments authority over suspected criminals. What they can't do to people who have not been convicted of a crime yet. But the last line has been redefined to include every living property owner in the USA, whether they're suspected of criminal activity or not.
"
No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a Grand Jury, except in cases arising in the land or naval forces, or in the Militia, when in actual service in time of War or public danger; nor shall any person be subject for the same offence to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use, without just compensation."
In the actual context of this line, means that they can't take the private property of a suspected criminal, without paying them for it. In fact, I think it could mean both suspected and one found guilty, imo.
But don't get too caught up in the 5th. I only used that as an example to show how the government oversteps in authority.
Trump says he like "taking guns first and doing due process later." Luckily he didn't get a bill that allowed that to happen, because he would've likely signed it, regardless of it's unconstitutionality.
Overstepping the constitution is how government grows in size and scope.