>>It replaced the Articles wholly, and illegally at that.<<
Not illegal at all.
Congress called the Annapolis and Constitutional Conventions.
The delegates to Philadelphia determined the Articles of Confederation could not be improved (they were right) and drafted a form of government that met the needs of the Union.
Said delegates submitted the Constitution to Congress. The Confederation Congress of the United States did not have to pass the Constitution to the States. It did.
The legislatures of the States did not have to arrange for popular elections of delegates to State ratifying conventions. They did.
The States held special conventions of the people’s delegates. They did not have to ratify, but they did.
Our beloved Constitution is perfectly legal.
It is remarkable to see the number of people prepared to argue against the obvious.