
For me personally it's cuz I will prefer one ml over the other and nitpick on the others lol, their dynamic can be written badly too if the author isn't good enough of a writer. The MLs need (for me at least) to have a good relationship with each other too instead of being overly jealous of one another. Not to mention that my fav ml will definitely lose screen time because god forbid the MLs to have bromance with each other
tldr: my fav ml won't be the only one and only and I'll hate the other guys (unless well-written but they rarely are)

You do have a point lmao (or more than one). The reason I love reverse harems is probably the extension of my second-male-lead syndrome, this way if everybody is endgame there's no favorite male lead left behind and nobody is left broken hearted by the end
However it's also true that the good ones aren't a lot, just like there are very few harems with a male lead that are actually written well. And also, when there are more than 2 love interests there is bound to be at least one of them that isn't properly developed as a character and is forgotten in favor of the "main" male leads. It all depends on the author's skills
everyone's disappointed that this is a harem while i smiled ... we haven't had a good one of those in a bit