If a Christian relies on edicts of theologians to validate their belief in something it is easy to be misled. In this case by looking for councils to determine what is, or is not Scripture it is easy to miss the beautiful working of the Holy Spirit. Christians recognized the Scriptures very early on. For example, the Muratonian Fragment which includes all but a few of the books found at the end of the NT dates back to 150AD. No hierarchy with the power of the State behind it established this, it was Christians led by the Holy Spirit.
The other issue in looking to councils of one church ignores that at the same time that the allegorical view of Scripture was emerging a literal school of interpretation already existed. In other words by relying solely on those that came later, acting as if those that were present at the beginning had not already established something, a Christian can fall into the trap of only seeing part of the truth.
The authority of the Church is very much dependent on the Holy Spirit and not at all dependent on "edicts of theologians". If it were, the Catholic Church through the centuries would have been captured by Montanism, Arianism, Pelagianism, Donatism and every other enthusiasm and split-off movement that came along, since as you know Montanus, Arius, Pelagius and Donatus were members of the long (and still continuing) line of error-prone theologians including Martin Luther, Fr. Hans Kung and Fr. Robert Drinan!
Being dependent on the self-described "leading of the Spirit" of any "individual" theologian is always going to be prone to error, since it is so easy to be misled when one is acting as a "lone ranger" cut off fromn thr Apostles and their successors.
That's why the Councils are so important. Whenever there is a major controversy or crisis, starting with the Council of Jerusalem in Apostolic times, the leaders of the Church must gather to weigh evidence, hear testimony, search Scripture, pray ardently, discuss and debate (sometime heatedly) and finally grasp a Truth they can announce with confidence, "It seemed good to the Holy Spirit and to us..." (Acts 15:29).
If you disregard Councils, you are disregarding how the Holy Spirit guided the Church in every single century --- through 20 centuries --- until now: as Jesus promised, the Church has never been left an orphan or abandoned. And we have the evidence.
The Muratorian Fragment is part of that evidence. It illustrates how the Church over the centuries had to deal with controversies about the question of the canon. The MF includes at least one book accepted by Catholics and Orthodox, but which today's Protestants would list with the Apocrypha (Wisdom), at least one properly called patristic (The Shepherd, by Hermas), and some which are seriously dubious "...the new book of psalms for Marcion, together with Basilides, the founder of the Asian Cataphrygians."
And although the Muratorian Fragment lists most of the New Testament books, it's missing a few (e.g. Matthew, James, 3 John), and it adds several works which are not inspired.
You clearly state your view (not mine) that the Muratorian Fragment was Holy Spirit-inspired. Really? Is it accepted as such by, for instance, the Baptists? If so, I take it you accept the book of Wisdom? And omit John 3, Matthew and James?
Not me. I think the Councils' canons, being unanimous over a period of almost 1700 years, are more reliable than that.
"Those that were present at the beginning" on whom everything subsequent depends, were the Apostles. The Catholic Church is built on the Apostles, on the foundation laid by Christ, with the guidance of the Holy Spirit. I personally find any other foundation dubious.