Wouldn't be an Isekai without a love triangle where one girl is inevitably going to get hurt. Especially since most of these writers never have the balls to go with the polyamory ending
More writers have the balls to go poly than to have a clear-cut ending where one love interest is picked and the rest are cleanly kept away without wishy washy ambiguity.
Please tell me where this supposed trove of poly stories is, because I'd love to read that.
Though based on you saying wishy washy ambiguity, I think you're talking about something completely different.
They're talking about harem endings. And they're correct. If you count harem as poly, which we seem to be considering we're calling one girl having two girlfriends who have absolutely zero interest in one another "poly", harems are far more common in the isekai genre and adjacent genres than monogamous relationships. The "wishy-washy ambiguity" part comes from the fact that the protagonist doesn't usually officially end up with any of the countless characters in love with them, so that the reader self-inserting can fantasise about the protagonist ending up with their particular favourite love interest.
And that's why this is such a point of contention. I think poly-enjoyers might have the wrong idea that poly itself is hated, but in this thread harems and poly are being fully conflated. Harems are, narratively speaking, disgusting. They're Mary Sue bullshit, bad writing that objectifies women for the purpose of fulfilling people's gross self-insert fantasies. I get that there's a market for self-insert fiction, a massive one at that, but harem fantasies in particular reduce women to being property. Every girl in a harem story exists for the sole purpose of falling heads over heels for the self-insert, usually as soon as they meet and for no discernible reason other than "they were nice to me once". I loathe it. Absolutely, positively hate it. It is literally the single biggest problem with the ACG fiction bubble. But it fucking sells. It sells incredibly well, and for bigger series it sells figurines and merch as people chase their waifus. So it just continues proliferating and my hatred of it continues growing.
All of that to say, this is why I desperately hope this manga doesn't go down that path. I'm not opposed to reading about open relationships. But you will never see any of the non-MC characters in these stories having their own relationships. Not with each other, and not with third parties who aren't involved with the MC either. In my eyes, that is absolutely not poly. Because all of the characters exist only to serve the MC's desires, and have no desires of their own. There's nothing romantic about that, and it's certainly not a progressive depiction of relationships.