Why are Malphite and Corki still problems?!

I just finished a ranked match which we lost. But that isn't what this is about the fact that the Malphite on the enemy team went full tank... As a Lucian with about 4- 5 items at the time, he had a frozen heart and Sunfire and was able to delete me without his ult. And at this point, it is ridiculous how many champs there are that can do horrible in lane yet still instakill as soon as they find someone to kill.... Other champs like Corki is the exact same they will have one item finished and have 1-3 deaths no kills come bot or top and 3 shot anyone he wants with little to no counterplay all you can do is run.... And it even happens sometimes where the Corki will miss all of his skills yet he autos and the sheen proc alone will do near half of someone's hp... So he is rewarded for absolutely nothing he can miss anything and still have such a ridiculous damage output. I wish this would be put to a stop because I'm sick of all the champs that are ridiculously strong even if you lose lane really hard.. And I understand it shows I played Yasuo I can see where other people were coming from when I was playing that cancer champ. #plsfukinnerf