cuz it's a promo and there's no other cover to pick form other then the novels cover art.
bro its not even an official promo. It's literally somebody's fanarts.
the post here is just a promo even if the art isn't anything official, my point is there's no other cover to use but the novels. ╮(￣▽￣)╭
Sometimes adaptions will have different names, so I find it helpful to see the cover as it is easier to recognize. But I do think it's best only done before officials come out though
Why do uploaders always put the novel covers?? When the inside doesn't have the same quality of art.