To me, the best argument against this (as well as all the other myths, like character/account IDs or keeping particular weapons in particular slots) is and has always been WHY would that even be the case?
The problems are immediately apparent, thus it would be necessary to keep it secret, thus we can’t trust anyone “on the inside” to tell the truth. But why would ANYONE do that, when the easier and less risky solution is to just not do that? C++ (Well, pretty much all languages) have had solutions for sufficient randomness a single StackOverflow search away for decades. And I seriously doubt that every single person who has ever had the opportunity to poke around the code would all have the same attitude in regards to this sort of thing. Every single one saw that, for example, one’s Account ID was used as the randomness seed, and every single one said “Yup, this is fine, no problems here, let’s just leave it like that, we definitely shouldn’t change this?”
Overdamage is similar, in that having it wouldn’t really accomplish anything. Even coming at it from a position of “The developers are just actually evil” doesn’t make it sensible to implement, because there would be easier and less risky ways to be evil. The only thing it would do is make players hateful of each other for “stealing” “their” “deserved” loot, which could be argued fits into a motive of selling more keys to solo/small groups, but again there would be easier ways to do that, if that were the case it would be in their best interest for Overdamage to be publicly confirmed, and it would be at odds with other changes, such as the recent 100% rare dungeon drop change.