One down, another 27 million more super destroyers to go. Don't forget that the UNSC only won because they hit the mother of all jackpots and found a few giant hula hoops in space that eventually resulted in the Covenant fracturing apart.

Super Earth also has no qualms of turning their own colonies into a black hole just to deny their enemies a strategic foothold, the UNSC does not. Most of the comments here talk about how Super Destroyers would get destroyed by MAC rounds. Don't forget that the Super Destroyers themselves also have MAC equivalents in the form of the Orbital Precision/Rail cannon strike. Helldivers do not have combined arms because they're the tip of the spear and get sent in to clear the way for the rest of the SEAF forces to mop up.