Real elo hell isn't Bronze... it's promos
This happens to me really often and to a lot of my friends too; I win a bunch of games and now i'm in promos; all the sudden my teammates suck ass while Riot expects me to win 2/3 of my games.
Seriously, in promos, Riot purposely gives you worse MMR teammates than enemies, it's pretty messed up. With all that going on, it's no wonder that passing promos and actually moving on to a new division is so hard without a free win...
Think of how hard it is to get promoted in plat+ without free wins...