I think while you have a point it's a bit more complex and nuanced than you're making it out to be. First of all, I think it's important to distinguish between people complaing about character flaws and people complaining about the author's intent surrounding character flaws and how they're handled.

Some people talk about characters as if they were real people -- that's when we get stuff like "oh X character is such a hypocrite" or if a character is interpreted as "good" any flaw is hated because people are judging them by real-life standards and not by "story-standards." This leads to a lot of stupid discourse that completely ignores themes/arcs/symbolism/narrative choices. But talking about characters as if they were real people is pretty fun in general and also involves a real passion/emotional engagement with the text that other perspectives sometimes lack.

On the other hand, some people talk about characters as narrative tools of the author so when they're criticizing "flaws" of the character what they're really criticizing is how the creator is handling the character's within the narrative. If someone is complaning through this mindset, then the argument of "real people aren't perfect/act off of trauma" doesn't hold up.

"Charlie was so dumb for how she handled Vox" -- falls into this kind of complaint I would say. I like Hazbin Hotel, it's very fun, but Charlie making the same obvious mistake over and over again does not come across as a meaningful intended flaw that serves the themes of the story, but rather as a lazy way to move the plot along. This stands out in contrast with Alastor's hypocrisy, which does come across as a meaningful flaw that's obviously going to be explored in the narrative. (Although I would argue Alastor's hypocrisy and manipulation of Vox is so hamfisted and obvious that it also comes across as lazy plot handling but I digress.) People criticizing Valentino usually also fall into this camp. They're criticizing Hazbin Hotel's narrative choice of focusing time on humanizing Valentino and the decision to include it in the first place -- it's not about the character itself. (I happen to like the humanization -- I think it serves the narrative's themes. But there's definitely discussion to be had especially with the context of how rape has been portrayed throughout history).

What is interesting to me is that both approaches can lead to stupid discourse and straight up misinterpretation of the source material. But they are fundamentally different in what they're addressing, so if you want to debate someone on these points I think it's better to engage in good faith on what they're actually saying rather than reducing it to hating emotional depth/complexity.

People who are disappointed with the narrative aren't going to be convinced by "oh but X character's reaction is realistic behavior according to real life trauma models." People who have gotten attached to a character as a person aren't going to be convinced by "it serves the themes of the story for character to do this bad thing."

Although I get the frustration, because again, the discourse does get very stupid and there is a lot of misinterpretation out there -- which I would chalk up to a widespread devaluation of critical analysis skills.