It's possible people don't want superhero activism in their comics because it usually turns out terrible.
But that's basically like 90% of comics out there, even the ones from 1940. That's just nobody usually noticed the activism itself because the stories were cleverly written in such a way that nobody objected to it while making them think about it at the same time. The thing is-- current activism in comics tends to be too in your face about it, instead of teaching a lesson in an interesting, entertaining way.
1950's to 1980's comics--everything was an allegory. The superheroes' activism was there, but it was subtle and not so preachy. so nobody felt like they were being preached to, even if they might be. Even if a few people still complained at the time that the superheroes' political viewpoints didn't aligin up with their own, because you can't please everyone.
Modern comics: Blatantly preachy hell. Straight up tells you that if you don't think and act a certain way, then you're a sexist and racist bigot, etc. Hell, Marvel just literally made two new superhero characters called Snowflake and Safe space in an attempt to appeal to the young SJW crowds. It was done in such a way that it was like an old man going "How you doing, fellow kids?" But those characters just ended up being hated by literally everyone, even the SJWs themselves.
It's truly impressive when something is so bad that all the comic neckbeards, anti-sjws and sjws alike unite
together on the internet to vocalize how utterly terrible the characters were... I'd like to think that this was secretly Marvel's goal all along, but.... eh?
Edit: noticed that there was a word filter in place for a certain internet term. interesting. eh, whatever. let's just say the "wonderful" person was of a far-leaning liberal persuasion and that the other people were far-leaning right-wings. that leaves it at that.