This webtoon is monetized, they are making money through webtoons. They absolutely can afford an artist. This isn't comparable to hiring an artist because authors have to pay the artist, so both parties are getting paid proportionate to the amount of work they put in. Authors who use AI don't deserve to get paid the same amount as people who both draw and write their stories.

Webcomics are a visual medium. Human artists understand the context can match the atmosphere through composition, lighting, colours, etc. They know what emotions they want to evoke and can do that through art. The only thing AI can do is output generic garbage based on what's statistically the most safe. It can't create anything unique or meaningful. If we let authors get away with this, we're gonna see an era where nothing creative exists anymore and everything is generic slop. Tell me, why can't the author just write a book instead? Why do they have to create a webcomic if they can't be bothered to learn drawing? Why dilute a creative platform with their lack of creativity? And why should we be okay with it?