@HotGirlShi It's perfectly ok to criticize an author for their story direction, it's not childish to have a different opinion from your own. If the manga is successful despite my opinion of the author's writing, good for him, and yes there are people that like it, and that's okay too!
Regarding what you say about harem, I'll agree to disagree: the harem trope is made to stroke guys' ego, regardless of how girls are treated in the story. That's why most of the stories are incredibly toxic if transposed to the real world, as the only thing that matters is the male MC. Most harem is like that, but there are exceptions.