why you shouldnt play champions you cant like lee sin,or early game champs if you cant abuse them

got another duo silver 2 and gold 3 . silver 2 players vayne, gets raped in lane, goes even and does no damage all game while graves is 13-3 only dying to yours truly. Lee sin 8-9 doesnt gank for 10 min and when he does he dies, we also had 0 dragons this game. He managed to take 2 kills after i ult mid and jungle and put them at 1/4 hp and stun them so he finally lands a q. Darius the duo of the silver. wins lane vs irelia pretty hard 3-0 takes tower, proceeds to push the rest of the game dying to 3 man ganks and just getting caught out instead of helping other lanes and getting objectives, hes now 5-9 . The reason the pro's play these champions when they are on new accounts is becasue they know how to use them. If you are not getting a bunch of early kills as lee sin you might as well afk because you are gonna be useless. Same goes with alot of early game champions your job is to snowball the game which you shouldnt be trying to do as a gold 3 or silver 2 because you still dont know how to play especially the early game or guess what? you wouldnt be low elo!