why more people should be banned from ranked

last season i was in gold i was doing my provisional matches today and i got probably the worst player/troll i've ever seen i was jungle i asked for a leash and for someone to ward red at 1:50 our adc said he would then our support started flipping out saying we will lose if he does that. honestly i was like wtf? never heard anyone flip out so hard over a ward but whatever most people tend to be nice t their jungle early to get extra pressure ganks etc. then our adc died early in the game honestly its a setback but not the end of the world. our support started flipping out again he said"we lost top lane im going mid" then he went to gank mid and instead of helping he died to a mix of akali and turret shots ruining the lane control our mid laner had. he proceeded to go 0/5/0 not a single assist i literally watched him just stand and die. our sivir gave up and fed even harder going 0/10/2 this is ranked not some bs normal i feel horrible for our mid and top laner who were honestly really good but they went negative as well due to the immense feeding something really should be done about this. its been happening more and more with each season with no end in sight. honestly this becomes much less of a problem once i qualify most likely in silver and i'll work my way up to gold but still this barrier is too much for a lot of players and they just give up on ranked all together