I don’t get the whole ‘this person gets more l…

I don’t get the whole ‘this person gets more lines because they’re more popular’ like some of the reasons people are popular is because they got a lot of lines because they have a lot of center time. Like I don’t understand why people don’t realise that if the more unpopular members got more lines they might become more popular? Like for example Jin of Bts became more popular after Fire because he got a lot of lines and screen time.