whats the point

whats the point of role picking if people are going to do what this nasus did in one game? he mustve chose mid as a secondary. forcefully takes top because he got mid instead of what he wanted? and when will picking support or fill as secondary not get you support more than half of the time I get it that it helps a lot by assigning points but theres no enforcement on it. Sorry if this annoys anyone but it just annoys me when I get top and someone forcefully goes top when they got mid as their lane