why does Riot give you the most difficult people to work with in Promos

Riot has a way to know if someone is a troll, afk and toxic due to logs, it always seems to give you the shittiest of the shittiest on your team during promo's this last game it game me a mid laner who afk'd for 15 minutes, then when he came back the adc rage quit and just afk jungle farmed refusing to do anything else for not getting red buff, we won but only because ad renekton can 1v5, really wish riot would help you out to climb and not give you the shit stains of the earth, and this was promo to gold, so its not like its that low