Actually, Starlin did the Thanosi retcon because Thanos after the ending of Infinity Gauntlet quit being a nihilist villain stealing mystical macguffins and causing destruction in order to convince Death to love him, and became a hermit farmer who would occasionally help Adam Warlock or Silver Surfer save the universe. (See Infinity War, Infinity Crusade, Cosmic Powers and Blood & Thunder or even the recent Silver Surfer Rebirth)
Those Ka-Zar and Thor stories that got retconned in Infinity Abyss ignored Thanos's character development by regressing him back into a planet busting villain obsessed with mystical macguffins with no explanation.
I think the ''stupid machine'' Mangog uses to chase Deadpool is meant to be the same machine Orion of the New Gods uses to fly. That issue of Deadpool was a big mockery of Jack Kirby and his artstyle.
I think Mangog is not popular because he only has a few apearrances in comics and he never interacted with the Marvel universe outside of Asgard. Plus the fact that he kinda looks like the Pinky Demons from Doom and his cheesy bombastic dialogue makes him hard to take seriously.
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