General Discussion

But I'll start at the end: the fact that the specific terms of the Articles of Confederation were ignored by the representatives that drafted the Constitution, if taken at face value, means that there is no need to pay any attention to anything in Article V and there is no need to meet the threshold specified therein to call a constitutional convention and completely rewrite the current constitution. In fact, if the words of Article V don't govern because the words of the Articles of Confederation weren't followed, then its anything goes -- what would be the legal impediment for a random group of individuals from various states getting together, drafting a new constitution and saying it replaces the current constitution when its ratified by two states (or some other random number)?

So, to reiterate, if a constitutional convention is called pursuant to Article V, it can't make changes to the Constitution without the concurrence of 3/4 of the states. It says so expressly in Article V itself.

But if there is another process not governed by Article V, that process could be whatever anyone wants to claim it its. There is no governing law to limit the process. A better argument is that there was a process for amending/replacing the Articles of Confederation but it wasn't strictly followed. It might follow that the Articles were never lawfully replaced and for the past 200+ years we've been mistakenly following an invalid Constitution. Or it could be that the flaws in the process by which the Articles were replaced were cured when, consistent with the requirement that changes to the Articles be ratified by all of the states, Rhode Island ratified the Constitution in 1790.

This latter theory is far more likely to gain acceptance than the former. After all, what body could have found that the Articles weren't legitimately altered? There was no judiciary under the Articles. But there is under the Constitution and its highly unlikely that the federal judiciary would conclude that the Constitution was ultra vires.

So back to the bottom line: either Article V governs or there is no need to even bother with the 2/3 requirement for a constitutional convention --- there are no stated rules as to how the constitution can be altered.