please stop with this bullshit.
im serious. leblanc being good at assassinating is intended. she is an ASSASSIN. she is also intended to be able to get in, and get out safely and quickly.
if you look at all assassins they all have the same strengths/weaknesses as Leblanc for the most part. High burst, great mobility/safety, very low sustained DPS. also incredibly squishy if building to one shot.
Just play Leblanc. I mean it. Play her and you will see why she honestly needs help right now. you can shit stomp lane. and another lane. ive had games with 600 ap at 20 minutes, but if the enemy team organizes and groups against you building MR early you are basically useless.
Leblanc is a great split pusher but her fall off is immense. once she has to use all of her abilities to one shot late game she becomes dumpster tier as her entire kit is built around dashing in, blowing someone up and blinking out. if she has to use her dash to blow up or all of cooldowns she is basically left sitting their to inevitably die.
and that is her problem. tanks are a thing right now and leblanc is only ok vs them. she becomes a more burst poke oriented mobile mage later in the game and that's just not good when you have no wave clear without distortion.
I know her lane phase is oppressive and honestly disgusting. it is. there's really not much you can do in lane besides build abyssal, get zoned out, and try to punish her if she makes a mistake.
but she is so bad later in the game right now and hard to carry with that if they nerfed her she would just be garbage. she is already honestly near that in my opinion. unless you play out of your mind on her you will never carry a game.
you will kill a ton of people and look "good" but you won't win the games. and that is what matters. Leblanc kills people, she's not winning games. even her win rate says so right now.