It was Gruenwald's world, everyone else was just playing in it

Jim Shooter might have been in charge of Marvel editorial in the 80s, and writer/artists like Miller, Byrne and Simonson were creating whole new worlds of stories, but the real architect of the Marvel universe at that time was Mark Gruenwald.

Gruenwald's appeal wasn't in creating new characters - although he certainly had a crack at that - it was in sorting and organizing the greater mass of Marvel characters. Most of the villains that appeared in his stories came from earlier appearances in other comics, and characters with similar motifs and themes could be consolidated and filed into their right place.

It wasn't just in the shorter bursts of pure Gruenwald like Squadron Supreme, which was well ahead of its time, his kind of weird unification of concepts was most often seen in his long Captain America and Quasar comics. He would often get all the speeders together and have them race, or all the female charcters and have them fight, or all the wolf characters and have them growl at each other, or all the Red Skull-connected characters and have them try to kill each other.

The pinnacle of this was reached with his Serpent Society, which took every single Marvel villain with a snake motif, added in a couple more, and created a guild of villains who were much more powerful and successful as a group than they ever were as solo acts.

He could find a place for anyone, and was ruthless about disposing of anyone who didn't really fit into the idea of 80s Marvel, slaughtering dozens of lame villains at the Bar with No Name.

Gruenwald's scripts could be clunky and obvious, but could also find interesting things to say about the number of Marvel characters who use darkness as a weapon. This consolidation also created a powerful feeling of cohesion through the entire line, and just when the Marvel Universe was getting too chunky to follow, it felt like all the characters events were connected.

The writer/editor's influence is still obvious in modern Marvel comics, his ideas still being mined by current creators, and it has even stretched out off the comic page.

After all, he was once immortalised as Mobius of the TVA, a tiny obscure character that was more in-joke than person, and who has now become familiar to millions and millions of people who watched the Loki show. Owen Wilson's first film came out just a few months before Gruenwald's horribly young death, so he might have seen the actor on screen. 

And while Gruenwald could have no idea that Wilson would one day play a version of him in a massive TV show, you could bet he would have appreciated all those variants being put in their right place.