Why were Pseudo-Dionysius's works accepted as authentic for so long?

[Pseudo-Dionysius](https://en.wikipedia.org/wiki/Pseudo-Dionysius_the_Areopagite) was a 5th/6th century Christian theologian who claimed to be the Dionysius that Paul converted in [Acts 17:34](https://www.biblegateway.com/passage/?search=Acts+17%3A34&version=ESV) . This claim was widely accepted for almost a millennium, which afforded his work significant influence in medieval Christianity. I know that historiography has come a long way in the last 1500 years, but the idea that these works could have originated in the first or second century seems completely preposterous. Why, for example, were none of the writings of "Dionysius" quoted in the prolific writings of Clement of Alexandria, Origen, Basil the Great, Gregory of Nyssa, or Gregory of Nazianzus? Not to mention their complete absence in the Councils and in Western writers like Augustine. I see from the Wikipedia article that "Dionysius" had some early skeptics, but a number of medieval figures argued for the early dating, such as Severus, John of Scythopolis, and Theodore of Raithu. My question is: **what arguments did these and other early-date proponents make that convinced medieval Christianity to consider these works authentic?** I know that some of these writers had a vested interest in the authenticity of the works, but they must have made other arguments besides "I agree with Dionysius so he must be who he claims to be." What evidence did they cite?