That's all any legitimate council ever does.
And the fact remains that there were people within the Church who were not on-board with the final NT canon, right up until the end. Typically this meant that they accepted other books in addition to the usual ones. So, some of "us" knew exactly which books were inspired, but others of "us" didn't.
BTW, your observation really doesn't change anything. Who, in your view, is authorized to recognize that "broad consensus" and make it binding on every believer? In the view of the ancient church, that "who" was a council.
Who in my view is authorized?
Well, do you believe in God’s providence and His Holy Spirit guiding His church through the ages? If you do, then the answer should be clear... God’s spirit, the same one that guides every true Christian today guided them AND the churches they represented as they came together to formalize the canon.
Now, if you don’t believe this, then of course, the answer is they picked ans chose as they saw fit. That, by the way, is the liberal view of things.