The psychology of resentment hits so much closer to home in Joker than in John Wick. I felt a lot for the character and the tone of the movie is quite serious. Any of the forces responsible for a violence born from this kind resentment are already primed by corresponding social conditions (or perceived injustices).

I could barely stand to sit through John Wick because it was so boring (action sequences were so repetitive). There is little emotional resonance with the protagonist.

Arthur is being treated badly by society. That is so much more intense than loosing a loved one. — Craiya

I tend to agree, but this sort of gives a lot of people the OK to rebel against those (or the whole society) who treat them poorly.

Now to be fair, this sort of situation:

E.g.: The protagonist's parents were killed and so he/she decices to do the same to their enemy - the antagonist. This should automatically make the protagonist a so called false protagonist. — Craiya

Is equally problematic as revenge becomes justification for anything.

I agree with your overall point, but would suggest that people have a problem with Joker because it is too real. There are lots of people who feel left out of society. We already have (in the US), a lot of mass killings by those who feel voiceless (despite many being white males); people feel like Joker would encourage that. However, for something like John Wick, being a super-assassin is part of the premise. So no ordinary person COULD go on a similar revenge spree. John Wick comes across like Coyote and Roadrunner cartoons, Joker seems to be making actual societal commentary.

But overall I agree, both movies are showing a type of revenge violence, with potentially Joker being more justified (how many people did John Wick kill along the way before actually killing the one responsible for his dog's death?...why does he continue killing after getting revenge for the dog?).

I could barely stand to sit through John Wick because it was so boring (action sequences were so repetitive). There is little emotional resonance with the protagonist. — Nils Loc

Interesting, I was bored by Joker and liked John Wick...but that is likely tied to the fact that I almost never emotionally resonate with any protagonist (or antagonist before you go thinking I am sort of psycho, haha). Actions and moments may resonate, but rarely the whole character.

The psychology of resentment hits so much closer to home in Joker than in John Wick. — Nils Loc

Entirely agreed. I think that is why there are some people that whine about the violence in Joker, but don't even consider whether the violence in John Wick is also problematic.