Mention of John the Baptist in the Apostolic Fathers

I purchased a copy of Michael W. Holmes' The Apostolic Fathers: Greek Texts and English Translations, 3rd ed. (Grand Rapids: Baker Academic, 2007) at AAR/SBL last week. It is a crisp looking volume. The solid green cover allows it to sit nicely next to my NA 28, BHS, etc. Holmes has included a helpful Index of Ancient Sources in the back, so I decided to use it to see how often John the Baptist is mentioned in the corpus of the Apostolic Fathers. The results?

Once.

I may be missing something, but using Holmes' index the only mention of John, and the only time a passage related to John is obviously quoted/echoed by the Apostolic Fathers, is when Ignatius says the following in 1:1 of his Letter to the Smyrnaeans (Holmes, 249):

I glorify Jesus Christ, the God who made you so wise, for I observed that you are established in an unshakable faith, having been nailed, as it were, to the cross of the Lord Jesus Christ in both body and spirit, and firmly established in love by the blood of Christ, totally convinced with regard to our Lord that he is truly of the family of David with respect of human descent, Son of God with respect to the divine will and power, truly born of a virgin, baptized by John in order that all righteousness might be fulfilled in him...

This echoes Jesus' words to John in Matthew 3:15 (NRSV):

But Jesus answered him, ‘Let it be so now; for it is proper for us in this way to fulfill all righteousness.’ Then he consented.

I don't know what to make of this quite yet, but it is curious. Why was John either (1) hushed or (2) forgotten by those who would come to be known as the Apostolic Fathers? Why is John absent from most of their extent writings while appearing in the Gospel of the Ebionites, the Gospel of the Nazarenes, and the Infancy Gospel of James