“The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.”
Their comments don't track straight.
“Its sole purpose was to spell out what the government can do.”
Not really. It also says what the federal government can’t do. For instance, it can’t
“Their comments don’t track straight.”
Your problem is with the language “applies to the federal government”. The Constitution proclaims itself the supreme law of the land, and therefore applies to the states as well as the government. But the spirit of the prevfious poster’s words are accurate. The Constitution by and large dictates the powers of the federal government. The phrase about powers “prohibited by it to the States” refers to powers out of reach of the states by virtue of their having been delegated to the feds.
There are also various powers expressly denied to the states. For instance, the ability to establish non-republican governments. Some sweeping denials of power apply to the feds and the states at once, for instance the 13th and 14th amendments. However, I think more often than not, the phrase about powers “prohibited by it to the States” refers to powers out of reach of the states by virtue of their having already been delegated to the feds.