>>123566583fans may not write the show but they keep it going. if nobody watched the show, made content, got it trending, bought the toys etc there wouldnt even be 2 seasons. fan approval matters a lot in this sense.
also being a "fan favorite" proves that the character is likeable enough to have a character arc that people want to watch. by the time astruc wrote s2 he wouldve known people liked chloe and wanted her to be redeemed and that they wanted a miraculous team. he prepared to do these then backed out. thats bad writing.
also writing a character to be "likeable" is something you learn to do while preparing to go into this industry, working in the industry or just by looking at the people who watch what you will make. so you cant just claim "he didnt know she would get popular!!". he wrote her to be the lesser of the evils, and mainly used her to be the reason for akumatizations while making her not inherently evil like HM was. after she got very popular, he brought a more evil character to replace her, gave her episodes explaining her past and give room to grow, gave her a miraculous and made her give it up, showing the audience she had grown. then he left it because reasons. thats very, very bad writing.
also the "fans dont know better" argument is valid for every show that isnt miraculous ladybug. this show is literally known for its fancontent. the show is shit.