What I find funny about that framing is that, regardless of whether or not the theory has merit, a conspiracy theory by definition asserts that there exists two or more people conspiring with the intent to produce the alleged outcome. From what I understand, dead Internet theory alleges no such collusion or intent. I could be wrong but I believe that it merely suggests that the amount of bot-generated activity has come to dwarf human generated content to the point where the Internet is effectively "dead" from the perspective of its original purpose: humans sharing human knowledge.