Reiner and Bertholdt didn't just want Historia out of blind loyalty to Marley; they figured out she was the literal key to finishing their mission without getting killed or turned into mindless titans themselves. As the secret royal bloodline hiding in plain sight, capturing her meant they could leverage the Founding Titan's true potential or use her blood to gain immense political and military leverage back home. For Reiner specifically, it was also twisted hero syndrome, he genuinely believed that dragging her away from a doomed island to Marley was somehow "saving" her, even though it meant feeding her to the military machine. They were desperate, burnt ou and knew that coming back empty handed after losing Marcel and the Female Titan meant a one way ticket to execution.

In Marvel Comics, Doom doesn't just rely on standard magic or tech, he built a time platform to steal cosmic power from the Beyonders and stitched together Battleworld out of dying realities during Secret Wars. The Avengers aren't dealing with a typical villain who wants to blow up a city. They are up against a guy who views absolute multiversal dictatorship as a moral obligation because his own calculations proved he is the only variant capable of keeping reality from collapsing. If they try to match him on a cosmic scale, he dismantles them mathematically and magically. The only thing that ever actually takes him down is Reed. His need to prove he's better than Reed is the one blind spot in an otherwise perfect god.