Clement of Alexandria who betrays his association with this 'Mark' (= evangelist undoubtedly) makes reference to the same Pythagorean interest which in case you are capable of reading is spelled out in the Wikipedia article:This Mark then, declaring that he alone was the matrix and receptacle of the Sige of Colorbasus, inasmuch as he was only-begotten, has brought to the birth in some such way as follows that which was committed to him of the defective Euthymesis. He declares that the infinitely exalted Tetrad descended upon him from the invisible and indescribable places in the form of a woman (for the world could not have borne it coming in its male form), and expounded to him alone its own nature, and the origin of all things, which it had never before revealed to any one either of gods or men.
https://en.wikipedia.org/wiki/Tetractys
In other words, it wasn't 'popularity' in the Church which determined the correct number of gospels BUT A PRE-EXISTENT MYSTIC INTEREST IN THE NUMBER FOUR DEVELOPED FROM HERETICAL SOURCES. Indeed Irenaeus says as much when he says God through the Holy Spirit determined that there would be four groups associated with four corrupted gospels reconstituted in their correct form in the holy fourfold gospel revealed to the world at the time Irenaeus was writing no before.