Why are there so many members in K-pop groups?

The average size of the top 10 selling K-pop groups of the last decade is 9 members, there is even one with 23 members. The Pudding offers a few answers on why the bands became so large - it's a combination of the popularity of super-size groups, the growth of trends in casting, subunits, and survival shows, and the shifting roles within groups over time.