Yeah um shaco damage is all from autos unfortunately. I'm done building lethality in games with adc with ninja tabi ga bt and shit tons of shields. Just better off going triforce or cleaver then other bruiser items since everyone and their dog is a tank nowadays including the adc.
Even for assassins who aren't reliant on their autos attacks so much like zed and talon, its still cancer for backliners to have as much defense as they do. Like think about it on some ap carries theyre gonna have an hour glass, they could get tabi if they want it, then some have tanky items like roa and abyssmal mask and shield from supports and their seraphs embrace plus shields like ryze shield. Especially like against an ezreal with ibg lol what a fucking joke to fight that mobile of a carry with that much armor with an assassin.
Honestly feels pretty shit to play against even if you have like 400 soul essence stacks in the late game, those mid lane and adc can 1v1 single target assassins with little utility to their team beyond killing a carry.
Not to say the majority of games are like this. Most enemy players are not that competent to take advantage of all the things they can do to make assassins useless. But starting at like d5 it gets pretty damn common and its sadly easy to just be like nah fuck this shit why play a carry that takes mechanical skill, planning, careful target choice, etc... all this fucking shit that goes into playing an assassin the right way when i could just play sejuani or nunu and faceroll :/