I obviously did not quote a section referencing conventions to argue against conventions, though I am perhaps being generous in my assumptions of what is obvious. That you would resort to such misdirection is telling of your character. It is not the mechanism of the convention which is in dispute, it is the issue of state sovereignty.
There is nothing about the convention process which witnesses against the sovereignty of the state. That the ratification proceeded along state lines evidences their political sovereignty. If, as you seem to suppose, they were merely seeking the approval of a larger, whole national population through expediently localized processes, why then would they have bothered with state identities? Why, instead, did they not pursue this piecemeal ratification along the more natural lines of common geography and solicit "Blue Ridge Folk" or "Chesapeakers" or "Adirondackers"? Why did they not treat along ethnic lines and seek the approval of Scot-Irish or the Old Dutch? Why not break down the population according to religion and have separate conventions for the Quakers and Episcopalians? If, as you claim, ratification spoke of the will of an aggregate, then why seek the affirmation of nine states and not a like majority of the general population instead? Yet they insisted in recognizing, as unitary political powers, those pesky states (please investigate the word "state") which confound you with their persistent existence before, during, and after the Articles. I wonder, do you hold that France was created by the League of Nations, all evidence to its preexistence and continuance not withstanding?
A consistent application of your theory of demonstrable sovereignty would hold that the Irish, having engaged in a popular referendum to determine their nation's adoption of the European Union constitution, actually DISPOVED the political sovereignty of Ireland. You seem to believe, when it accommodates your pre-conclusions, that sovereignty is expressed through a singular government such that the extra-governmental ratification process which took place in each state disproved the very political self-determination upon which the very matter of the choice depended. The contradiction necessarily arises that one proposition, that the states are shown to manifestly NOT be sovereign by the action of the people, is used to support a second proposition, that a larger nationhood IS sovereign through the same popular action, even (and especially) when it is tediously state-defined. That is, you claim that the sovereignty of the states was disproved by the direct action of the conventions as opposed to the agency of the state governments *in order* to prove the sovereignty of a greater nation, the circumvention of its government not withstanding. For you, the identification of "the people" is hinged to government in such a way as to allow it to swing whichever way you think you need. You either believe in "popular sovereignty" or you don't.
Not only did you misplace the emphasis to highlight "CONVENTIONS" and not the pertinent "OF NINE STATES" (in an inflected language, this would demonstrate the genitive of possession), you left off the part which is absolutely fatal to your argument. I'll reinstate it: "..., shall be sufficient for the Establishment of this Constitution between the States so ratifying the Same." That is, upon ratification, those states pending membership came under the constitutional supremacy of the United States Constitution. As a corollary, any state NOT "so ratifying the Same" did not. So if, say, Pennsylvania had been a lone dissenter and never ratified the Constitution, it would be outside the union. If you do not agree that an independent Pennsylvania would be a sovereign Pennsylvania, and that states were therefore initially invested with sovereignty in order to be able to parley with it, then you are beyond reasoning.
My statement is in no sense a “misdirection”. It speaks to the issue of true sovereignty in that had the intention that states be truly sovereign then that would mean that they would have the right to withdraw. Hence, state governments were deliberately removed from the decision so that they could never ON THEIR OWN withdraw ratification by a legislative act which would be allowed under true sovereignty.
There was no national mechanism through which the ratification process could have been made in any case the decisions had to be made within the states as frameworks. But the Founders, particularly the greatest of them, DEFINED themselves as Americans and never denied that there was an American PEOPLE though it may have been spread over states and territories. Your alternative methods are utterly impractical and ignore the obvious advantages that defined borders provide.
Most of the rest of your post is too rambling and scattershot for me to bother with. You can check the post above for my thoughts on the Supremacy clause which by itself destroys any idea that states are sovereign.
BTW two states remained out of the United States for several yrs: North Carolina and Rhode Island. Both were because of sabotage and subterfuge by interest groups who stood to lose power. Both were also admant that they not be treated as outside the Union promising to get it right as soon as possible. Washington took a benign approach to the issue.