8/10 in promos but got placed in B5

Hi guys, I started playing league 6 months back.With bucket load of tears,blood and some help from my friends,i made it to lvl 30.I was a noob then,i got placed in B3.I degraded to B5 eventually.Then i improved somewhat,and tried to climb but i couldnt because of elohell.Then i thought maybe if i do well in preseason promos,i ll end up in higher division...Nah...I went 5/5 and ended up in B5.Then came our beloved ranked season 7,i tried my best and ended up 8/10 in promos(one lose was due to feeders and one was deserved);i know i wouldnt cross bronze,but i was hoping to get atleast B2 or B1,but as usual i got B5.If im gonna keep ending in B5 i dunno what is the point of conducting promotional games.