It makes no sense at all.
If it's trying to criticize isekai settings, then why does its setting barely resemble any isekai out there? I can't name a single isekai which actually goes out of its way to glorify what you're talking about. "pinpoint-accurate" my ass. So instead it creates a nonsensically dystopic Handmaids Tale-esque shithole and says
"See... This - is what the average isekai setting totally looks like. Look what those losers want to live in! Tee-hee-hee! It would be sooooo awful for women to live there, riiiight😕?"
Really? Then name me a single isekai setting which actively prohibits women from being adventurers or in positions of power and treats this like a Good Thing. No, you cannot. This would be like shitting on all science fiction and fantasy because John Norman of Gor exists.
Funny thing is, I don't even like isekai. It's a dogshit genre for completely different reasons but that's beside the point. Even then I can still say JK Haru was an incredibly unfair "satire" of the genre. It is a 31-chapter long gaslighting session so far off its own up ass it can chew its own brains. To begin with, it criticizes a version of the genre that exists exclusively in the author's head, which is absolutely fucking ridiculous.
This is not your "average isekai setting". Nor is it a "male power fantasy". Absolute fucking bullshit.
If it were really one, Chiba would be SWAMPED in so much exotic pussy he'd forget about Haru by the second chapter. Male power fantasy isekai is about getting away from the world you were from, not SIMPING for it. But he doesn't, so he has to bother Haru which gives her another reason to complain and be morally superior. It is a victim fantasy...
Spoiler: SPOILER FOR CHAP 25
It is not "asking us to think about how a fake dreamworld designed solely to satisfy straight male power and sex fantasies (i.e., the traditional slave, rape, and harem stuffed ero-isekai setting) might feel to an ordinary young woman suddenly trapped within it." It is asking us to think about how a fake dreamworld designed solely to make the protagonist look as morally superior as possible would feel to an "ordinary" "young woman" (the male author's self-insert which he uses to psychologically distance himself from the character whom he refuses to admit he is the most like: aka. Chiba, and to vicariously experience the social and narrative privileges of being a woman, sort of like Andrew Dobson's female characters)
Chiba doesn't reflect any part of otaku stereotype other than being creepy and misogynist and obsessed with anime.
...And for some reason he likes Haru. Have you even seen the purity complex these incels have? Most of them would rather die than shag a hooker. Realistically, Chiba would probably go after local girls - sort of like an American sexpat in the Philippines. He wouldn't like Haru at all. If he hates his world so much, he would view her as a reminder of a shitty, embarrassing place he wanted to escape from - but that would make have to make sense.
If I were in his position, I would have gladly fucked off and never seen her again. Or quietly killed or maimed her before doing so. No "hero" nonsense, no "protect women" bullshit, just "happily abandon women who were shit to you and never think about them in your lives."
Writing a character like Chiba to mock otaku is like writing a character to ridicule muslims - then making said character a whiskey-chugging alcoholic whose favourite burger is the bacon butty. It does not work if you have the slightest goddamn familiarity of the stereotypes associated with either group.
Also, weebs are self-loathing as fuck, too. What the author is supposedly saying is "tee-hee-hee! no girl wants to be with you, have you thought of that?! Hmmmm😕" but do you really think these neckbeards haven't already told themselves that at least a hundred times? Look at their fucking forums. Look at /r9k/.
Do you really believe this is a new and novel idea? It's repeating a miserable porn addict's internal monologue to himself, which says more about the author than any imaginary person he's trying to criticize.
Conclusion:
This is not the "average isekai setting". Far from it. The world of JK Haru is a specific porn setting Hiratori probably invented in his mind, jacked off to, then wrote JK Haru in after realizing what his overbearing, abusive radfem mother would think of it as a way of coping with the guilt. I know this may not be true but I hope to God it is. It would be so fucking funny if it were.
tl;dr Isekai is shit. Haru is shit. Chiba is shit. JK Haru is shit.