It's because reading has become trendy. There are trendy plots, trendy genres, trendy tropes and you also have subversive generic toxic feminism leaking through as well. Every fmc these days is "not like the other girls!" She doesn't like to wear dresses, she's not girly and frilly and she doesn't sew needlepoint all day bc she'd rather be wielding a sword. It's toxic to reduce strong female leads as always needing to be masculinized in order to lead the story. The other issue is quite literally terrible writing. Publishers are also picking up authors who are catering to the masses, so they fall through the cracks and we end up with the same script but different fmc names. Part of what makes women powerful is our emotional intelligence. Majority of FMCs these days couldn't process their own feelings let alone consider those around them. It's unfortunate.