It takes a lot of practice to convey texture in illustrations. Ribbed fabrics in particular present a unique challenge to new artists because of how they emphasize body shape. The lines will warp as they follow the character’s natural curves.
The creator also needs to be aware of which articles of clothing tend to be ribbed. (Spoiler alert - it’s usually knit textiles, like sweaters!)
Which of the illustrations below do you think uses ribbed textures the best?