Ranked Matchmaking system is crap

Ok " title " BUT can someone for fk sake explain me why there is something like "Primary role" and "Secondary role" even when i every f*ing time get secondary one ? im like TOP-MAIN JUNGLE-SECOND and from 10 games i get 8 times jungle and to be honets NO i dont want jungle because im bad at jungle and i dont even like that position so pls Rito tell me what am i supposed to do when i get jungle then i have to quit game because im definitly not playing game where i fail and then get flaming team about how they all should report me because i cant get 20/0/20

So what should i do .......................... rly ... tell me pls ... beacuse i dont know anymore [slayer-jinx-unamused]