
Taegu backstory is involves Yeongwoon, that why it needs to be told. We are missing information about what happened to Yeongwoon after he left home and Taegu has involvement in that. Also, we are finding out why he decided to help Yeongwoon when normally he would have just ignored his situation like he was doing before.

maybe the also the reason they mad because they thought this is the plot of the hyung and backstory of him which makes any sense cuz as we can see that this is not a sadness plot of hyung that makes me feel sympathetic towards him.. this episode just literally say about our mc from hyung pov without the sad story about this gangster.. even he knows he is scumbag and move on with it..
people still misunderstand this plot as for the gangster and not mc.. which is not about the hyung but towards the mc… i hope ykwim right?
I actually teared up a bit when Yeongwoon was smiling.