Twitch is the ADC that keeps kog in check

Even when kog was in his reworked double attack speed cap state twitch was the only one that had the damage output to make the kill 1 for 1 against kog and they still hold that general relationship since they are the premier hypercarries that are notorious for wiping out the enemy team with the proper level of "protect the carry" team play.

I can agree that twitch's kit needs some retuning but kog maw would have to be looked at simultaneously. Kogmaw and to a degree kayle warp the balance of on hits for all the potential melee AA carries, and are easily some of the more blatant examples of the need for a difference in the power offered for melee vs range in items. Until itemization is changed his kit will always be on the strong end and will require the answer of twitch to not end up as the sole team fight hypercarry adc.

For twitch a lot of the power in his kit is from a combination of his ult and his passive. I think flat true damage isn't very healthy in that it will always show itself to be overtuned or undertuned. It should have its power redistributed to scale up with stats. Overall I dont think that it is the best route to just flat out nerf the kit. I think he is just in need of having his power redistributed.