As a longtime fan and writer, my opinion is that celebrity catfight fiction isn't dying, catfight fiction in general is dying. The number of stories on everybody's site is decreasing, and there aren't a lot of new writers to take their place. I'm not sure why. Maybe because videos weren't as plentiful 10 or 15 years ago.
Admittedly a lot of other reasons sited are true. I don't write as much because of time, and also stories now are a lot more complex than 15 years ago. I do find myself writing stuck in a rut with story lines. However when I read new material, that jump starts me and gets me going.