You literally prove that you have no idea what your actually taking about. Rengar kills you with his passive because he lands all of his abilites to recieve the passice full ferocity, talon has to hit his w he will never kill you with just a r, zed has to being either autoing the whole time after his r or has to atleast his you with a q and e in most cases both to fully oneshot you, leblanc has to hit you with a q and another q along with a w to one shot you, for fizz he has to hit you with a r,w, and q e is mostly used to get in close or used as a escape afterward.
Also why is it that people think that assassins are divers, the reason assassins are considered high risk high reward, is for two reason one being they are squishy every assassin is squishy unless they build otherwise and two if they fall behind they will be useless for the rest of the game. Lastly the reason they are classified as assassins in the first place is because they have a escape, pykes mobility is a engage as well as escape. For rengar his double w which is were he gets the cleanse which requires him to hit everything as well is used as a escape his he falls his asssassination. Also if they fail the assassination, which is actually a third point of why they are considered high risk high reward, is because hey are useless without their ult in most cases, if they fail to assassinate in teamfights they are useless for the rest of it and are just easy targets. They can also fail to escape as well getting caught by hard cc.
The fact that you got upvoted proves to me that most people dont even understand what assassins are and are just butt hurt because they lost to them in lane. The reason assassins are doing well is becuase early game is so prevalent and early game dmg is high as well. It has nothing to do with their basic designs.
I would prefer if idiots like you and the rest of the people who upvoted you would just stop posting because its because of you we got these failed assassins reworks in the first place, rengar rework reverted, leblanc rework reverted. They where failures, and it all stemmed from the fact that low elo players didnt know how to stay with their team, check the mini map, and understand basics of the game.