The reason so many people want RDJ's Doom to be a Stark variant is because the alternative is that Marvel, and by extension Disney, is in desperation mode. "Iron Man did well, Iron Man was played by RDJ, we want this movie to do well, we need to throw a dump truck full of money at RDJ again."
Furthermore, RDJ, as much as I enjoy his performances, always plays the same character in any movie that isn't Oppenheimer. If this Dr Doom isn't a Stark variant, it's going to be weird at best and terrible at worst when he acts like Tony Stark.
Yes I've been waiting a while for it and Orville. Sucks how long its taking for Orville the most though, that show is way to good for what it's billed as.
Seth McFarlane hoodwinked Fox Entertainment quite well. Sold the first season as a sci-fi farce, but used the opportunity and funding to turn it into a workplace TNG. Still tackling hard issues of our time, while taking the piss out of its predecessors.