Fewer characters to draw
Same thought.. At first i thought it was because it makes the MC and/or ML's backstory interesting which is a common trope from manhwas I've read so far. Then maybe because it catches the sympathy of the reader. And lastly it makes the job of the artist/drawing easier fewer characters fewer details to place.
Kdramas too it’s either a sick grandma a sick mother or a sick father and they are all unconscious
(⊙…⊙ )