This whole line distribution topic also really annoys me, especially as so many fights break out over it all the time
Fans kinda always want their favorite idol to either have most lines or have everyone the exact same amount of lines or they get angry.. which ofc rarely works out if your fave is not the main or lead vocal

Often I feel like many Kpop fans would do better just stanning solo artists, would save them a lot of trouble
I have no strong feelings on positions, as they not always make sense to me, its kinda fun though to have them (apart from it being another reason for constant fights)
Vikkis points is really interesting though, I acutally also do not remember to see many fights about dance time distribubtion. I think this has a lot to do as idols are mainly seen as singers, thats also why many idols are called talentless and undeserving, as many fans refuse to understand that kpop is not only about singing and you need other talents too..