I have some concerns with the new ranking system

So id like if someone could get this straight for me. Hopefully a rioter. So say i Queue Mid jg. and i get autofilled support, i win the game. will the points for that game go towards my support rank? If so thats the dumbest thing. why would i want to play a game where the roles that dont matter to me would rank up? I feel like that would ruin the progression towards ranking up. Only reason i play league is for ranked. If i cant Rank up normally i feel like that would ruin the game for me.