Board Thread:Questions and Answers/@comment-62.1.165.98-20181011205728/@comment-17964257-20181011210340

https://swordartonline.wikia.com/wiki/An_Incarnation_of_the_Radius#Trivia

> According to the author of the series, Kayaba Akihiko likely decided to abandon the use of An Incarnation of the Radius due to believing that no one would have been able to defeat it.