I'm not sure if I agree fully with this.
I'm primarily an artist. I write for my own webcomic, but I'm definitely not great at it.
I'm sure that there are others in this situation, where they are more interested in the art side, rather than the writing side.
I absolutely appreciate that artwork is worth money. There's no arguing about that. However, if both the writer and artist aren't expecting to earn money off a project, I think that it's fine to at least ask if anyone is willing to do art for them It might not be likely that they'll get a response, but it's not like anyone is forcing anyone to do anything.
An artist might lack amazing writing skills, but might be great at visual storytelling and have a lovely art style. If an equally fantastic writer is offering their story up for someone to do art for, they can both benefit. The artist might gain the recognition they deserve because of the writer's great writing.
Obviously if the writer is expecting to earn lots of money off a project and they expect the artist to work totally for free, that's a completely different story...
I don't know, that's just my thoughts as a relatively new comic artist (though I've been doing digital art since I was 9, so almost 10 years worth of it!)