What is it about Twitch that makes Riot resilient to buff him?

Especially his Contaminate damage. That thing is just useless early game. Now, I do remember back before they nerfed it when Twitch was a huge lane bully, and I'll admit that someone who has a late game as good as Twtich's shouldn't be the huge lane bully that he was. I remember when you could get someone to like 40% hp at level 1 then Expunge for easy first bloods. However, much time has past since then and Twitch's laning is now just a shadow of his former self. Seriously, whenever I do good in lane with Twitch (as a Twitch main) I feel like it's either because the enemy made a mistake or because my support made a godlike play. The fact of the matter is that Twitch just does 0 damage early game. Twitch easily has the worst laning of any ADC, including Vayne I'd say. I think a good buff for Twitch would to be to keep his passive and Contaminate the same damage per stack, but increase the number of stacks he can get.

But all in all, what is it that makes Riot so resilient to buffing Twitch? Is it because his kit is unfun to play against when ahead? The fact that a Twitch with a lead can solo carry the game? What is it about Twitch that makes Riot not want to buff his laning, but champs like Jinx get to have an above average laning along with a great late game? All I ask for is a few simple buffs. Maybe buff his AD. Give him more AD on his ult. Increase the Contaminate damage a little. Make him be able to stealth quicker. I dont know just do something! Whenever I play Twitch I feel like I am useless to my team until I and 4-5 items into my build, and by then he game is usually decided pretty much/