The Masoretic does not match the Hebrew Text that the New Testament primarily quotes from, they either quoted from the same source the LXX were copied from, or they misquoted the Hebrew scriptures all together.
You are implying that either they misquoted the Hebrew or that because God can do what he wants, it's logical to believe that when citing OT scripture He can change it for some deep esoteric teaching that no one but you has even suggested.
Tell us, what deep hidden teaching does changing 75 to 70 have that has ultimately caused the early Church to fabricate an entire OT that never existed before?
The Masoretic is the Hebrew Text from the Palestinian Jews.
You cannot present a Hebrew Text that the so called Septuagint is translated from. It is just a Greek translation supposedly of the Hebrew.
In other words, the changes made by the so called Septuagint are not found in the Hebrew. But everyone wants to accept this so called Greek Septuagint because it matches the Old Testament quotes fround in the New Testament.
With the New Testament you have two major different Texts that it is translated from. 1.) Textus Receptus, also called the Majority Text, or the Antioch Text. 2.) Westcott/Hort, also called the Minority Text, or the Alexandrian Text.
Because Westcot and Hort depend heavily on the Alexandrian Text in their New Testament translation, then their Greek translation of the Old Testament quotes will naturally fit the Alexandrian translation of the Old Testament. Which is known as the Septuagint. The oldest translation being found in Origen's Hexapla. 200 A.D.
So, Modern Bibles most all use the Alexandrian Text for the Old Testament and Westcott/Hort for the New Testament. Whereas the KJV uses the Masoretic Text for the Old Testament and the Textus Receptus for the New.
There is a certain axiom Bible translators use. You never opt for the easiest. But of course that has been abandoned.
Deep esoteric? No. For example: (Matt. 21:16) has Jesus saying "Yea; have ye never read, Out of the mouth of babes and sucklings thou hast perfected praise?" This comes from (Ps. 8:2) in the Hebrew Old Testament. But there it says, "Out of the mouth of babes and sucklings hast thou ordained strength." It simply means Jesus is associating praise with strength. And don't we as believers find this to be true?
Lees