90% of harem are midless idiot women who are in heat and only want to be recognize by the ML, want to enter ML pants or are only there to boost ML ego!!!
There are some good harem though, like Isekai Nonbiri Nouka or Otome Game no Hametsu Flag shika nai Akuyaku Reijou ni Tensei shite shimatta, but mostly are Zubats that never learn new moves nor evolves ever, some don't even level up at all!!!
And sadly, there is also the pedo harem that honestly is the worst!!!
So, several harem are only trash to attract male readers penises or give an excuse to use another rattata: fan service... that honestly, 85% of it is trash and some should be illegal (little girls fan service)...
So Harem and fan Service if they use it in an intelligent way and funny way and part of the story, many times a parody of itself it can be great part of the story... like a Zubat that have been take care correctly, sadly those are becoming rarer!!!
In the first games you could barely walk in tall grass withour finding a Rattata, they were everywhere and many began to do jokes about it!!!
The same Zubats but in caves, it is because Zubat that I used to buy repelent before entering a cave... well... after I was sure I got all the pokemon in the cave, that was before getting fly!!!
In my original country they sold Pokemon in english when I began to play it, that is because it takes time to get the translated version, and being USA our mayor customer many people used ro play games in English even though they didn't understand... when we gor the Spanish version they kept the English names, even in the anime, because all kids and teens recognized the names in English...
In Latin America we rarely translate the names of chatacters from.English games and novels, we used to, like Bruno Días (Bruce Wayne aka Batman), but we don't do that much anymore... that is why I got really annoyed when a Fremch friend of mine was saying I was naming wrongly the names of Harry Potter characters, I read the first 3 books in Spanish with the English original names, but in French they changed the names... this was before Harry Potter was internationally popular as it is now...
Honestly, harem are the Rattata and Zubat of mangas!!!