Most of them are horribly written and are annoying characters. Also it seems like they can't live without being saved by the guy or being after him because they always like that main character it's annoying that they can live by themselves. So it turns into a disgusting Harem where all the girls are annoying and we weak as shit. I have more to say but I rather not going on a rant or I'll never stop.
To me it's because they are often written as helpless maiden in need of the hero to be saved and without said hero they basically aren't interesting...
Which is a huuuge and horrible shame to me --"
So yeah I basically agree with NiceDove (and I did comment an essaie above XD)
to me they're just a bunch of burden
I haven't read this yet but here's why I dislike harem. The bachelors and bachelorettes are EASILY replaceable and they add NOTHING to the story. If one day that one of them is suddenly gone, it wouldn't make any difference at all. Also as what the other's said, they are straight up a burden to the MCs and holds the story back from developing.
So I've seen this many places and I still don't understand it. I've never been bother by the women or girls unless they were written to be terrible people. I know better than to ask people to stop(cause that's got some people really mad at me) and now I just want to satiate my curiosity for why people think this way. I'd love to hear any opinions on the matter.