It doesn't. How a song charts in Korea for globally successful group is of zero consequence. Examples are Twice and Stray Kids. They do not chart well in Korea, yet are #2 active girl and boy groups globally in terms of revenue, since Korea only contributes a couple of percent of their total revenue.
If YG bypass Korea in their promotions and marketing for BM and produce on of the future top groups, you may see other and even most big kpop companies take the same route.
Oh, Im not disagreeing with that, just more how it relates to the topic of this thread which is "should we use Youtube chart instead of melon chart to determine biggest song in korea" ?