The logical flaw in this is that it is not a Masters of Arts degree, as made popular by North American and other Universities in the last 100 years, which is an earned, postgradute degree.
The Master (as in Teacher) of Arts degree is a licence to teach, the authority to grant such licences having been delegated to the University by the Pope.
In the Middle Ages the Church controlled strictly who could teach. Students normally entered the University at about age 14 and completed one stage of their studies at age 17 or 18 but they could not receive the licence till the age of majority - 21 - seven years after matriculating. Instead they received a B.A. degree and waited for the seven years to elapse. Some studied further, such as the quadrivium.
So the M.A. is Cambridge University's first degree for students and should not be confused with recent concept of Masters degrees (earned postgraduate degrees).
The Artium Baccalaureus or Baccalaureus in Artibus
was awarded upon completion of studies but had limited significance,
the M.A. being awarded about seven years after
Matriculation provided the B.A. was awarded.
[C.f. the Baccalaureat in France today, awarded upon leaving school at age 17/18]
Studies were based on the classics, particularly the ancient Greeks such as Aristotle, plus more recent scholars such as Duns Scotus, Peter Abelard, William of Occam, Anselm, Thomas Aquinas and Roger Bacon.
For a while there was a M.Gram. (Magister Glomeriae) degree, essentially a teacher training qualification for becoming a Grammar School teacher, which concentrated on the Art of Grammar - particularly the teaching of Latin. God's House was founded for training for this.