As I understand it, a presidential candidate needs to secure 270 electoral votes to have a majority and thereby officially win the election. As I also understand it, when the joint session of Congress is presented with the electoral votes, they go through each state in alphabetical order, and either certify or object to the allocation of those electoral votes. It is certainly possible, and indeed happened yesterday, that one candidate reaches the 270 vote threshold before all the states were completed. At that point, it would of course be impossible for another candidate to amass 270 votes even if all the remaining states' votes were successfully objected to.
Why, then, do they need to continue through the rest of the states? Why can't they just declare the next president as soon as one candidate reaches the 270 vote threshold? It seems like a waste of time, especially if representatives can still object to states' votes after one candidate has already secured enough votes to win (as indeed happened yesterday when a member of the House of Representatives objected to the votes from Wisconsin).
Is this a mere formality, or is there actually an official rule that a president cannot be declared unless all of the states have been certified?
The relevant sentence in the Constitution (Amendment XII) states:
The President of the Senate shall, in the Presence of the Senate and the House of Representatives, open all the Certificates, and the Votes shall then be counted.
Is it that a very literal reading of this means that the president of the senate must open every single certificate before any of them are counted? And if so, what does this rule serve to accomplish?