Tl;dw - Unlike China and Japan, medieval Korea followed an extreme school of Confucianism that emphasized hierarchy and age over practicality. After WW2, the South Korean ~~dictatorship~~ government used this tradition to cement their own power. The video argues that these have made South Korea an extremely hierarchical, and in particular, sexist, society. A video game's refusal to sexualize a female character for their (mostly male) audience was thus seen as an attack on the system. A female artist at the studio was accused of being a 'radical feminist', and either fired or resigned to appease fans.
Edit: As Denjin pointed out, it should be Ming Dynasty and not Tang Dynasty.
I absolutely adore Moon Channel!
My favorite is the video "Why Are There No Good Christian Games?"
It gave so much more clarity to the lifelong issues I've had while growing up Christian.
Cmon, Doom doesn't count? You're literally killing Satan