The flavor of propaganda is irrelevant to the point I made. Authors used to use allegories to instill subtle messaging. The problem is, the last few generations grew up on picture books and TikTok, so they have the literacy skills of a turnip. In this particular instance Bandman and the Joker fictional characters that exist in a fictional world. So a one off crossover to inject a literal NAZI character into their separate world just so the arch villain of Batman can virtue signal how even he isn't as bad as those guys is just on the nose messaging. The original Joker character was created in 1941. The crossover wasn't even produced until 1996, 55 years later. The supplied image above is from 2020. None of this is even in line with the Batman/Joker canon. The Captain America and Red Skull world was built around a real world time period, so those topics and interactions are not forced, as it's core to the world building of that series. Other notable examples of inclusion without force would be Magneto's character background. His background is his motivation for his actions, but quickly evolves into humans vs. mutants as a subtle allegory for racism and segregation. The method of delivering the message without being preachy through the positive lessons instilled by Professor X is why people didn't take issue with it. What most people don't realize is, the American comic book industry basically collapsed around the mid 90s resulting in multiple major companies going bankrupt and selling off assets or rights. Then new production companies started churning out all kinds of slop just to make a buck. This led to outsourcing the material to all kinds of low quality authors who started pumping activism into the franchise. This problem persisted up until the distributor collapse of 2020. This is why both editions of the Joker and NAZIs take place at these two time periods, because it was the last gasp of a dying industry. Most of the people reading comics were the people who grew up reading them. As it turns out, those people don't like being preached to. They didn't like the right wind moral authoritarians preaching in the 60-80s, and they don't like the left wing moral authoritarians preaching now. The younger generations weren't big on American style comics to begin with, so the forced injection of modern politics drove them away to Japanese manga. When you contrast American superhero comics to manga, the difference in messaging (or lack thereof) becomes extremely obvious. Most manga follows the tradition of unique world building and hero fantasy, without modern political preaching. This is why the manga industry even in the US is EXPLODING, because at the end of the day, people enjoy this form of media as an escape from modern reality.