The CURRENT KJVO myth is based upon the party line of Wilkinson, Ray, and Fuller. Those latter two authors copied heavily from W's error-filled book, and, unlike their predecessors, had the power of modern media to help them hawk their wares.
Now, while I acknowledge without hesitation that there have been KJVOs ever since there's been a KJV, it was not a well-known nor popular stance till modern times. There was a long period when the KJV was "the Bible" to the English world, but as time passed and the language advanced, it was apparent that the KJV was being left behind, and new Bibles were made. Until the late 1950s, the KJVO issue was largely discussed in scholarly circles and didn't involve the general public too much. However, as sales of modern Bibles began to perk up, those who actually believed the KJVO myth began to team up with authors who recognized a "cash cow" to publish pro-KJVO stuff. With the help of modern media and printing mechinery that could turn out books by the million, the myth was established throughout the English-using world. This is the same myth that originated with Wilkinson, Ray, & Fuller, with some modern additions tacked on by the likes of Ruckman, Riplinger, and a few others. Most of the others simply re-package the old party line garbage into a differently-colored bag.
There were others before Wilkinson who insisted Psalm 12:7 is about God's words, but that view was little-known and less-believed before modern times.
As for the KJVO poster-boy, Dean John Burgon, he had but one modern Bible to consider...the RV...and even now, few believe it's a very good version. Burgon felt that the Textus Receptus could stand a thorough revision, and he was open to a new Bible being made that took ALL the mss known to him into account. He didn't live to see the newer Bibles now in use, and many other mss have been discovered since his death. I mention Burgon because some KJVOs recognize him as the founder of the current KJVO myth,(Dr. Waite's "Dean Burgon Society") which he was NOT.
While we should be cognizant of the fact that there were a smattering of KJVOs in the "old days", they drew very little attention in their lifetimes and there was not a core of "KJVOers" as there now is, who stick to the one set of doctrines, even though they've all been proven false. The current KJVO myth is a modern thing.