Nothing else can touch AD carries unless you're playing something with huge instant burst and little to no animations like Leblanc/Katarina/Zed
and
both have some pretty solid counter-play.
Kat's entire strat is throwing her squishy self into the middle of multiple opponents, pressing R, and hoping for the best. Pretty high-risk with plenty of reflexive and tactical ways of dealing with her.
Similar deal with Zed - his ult takes a while to set up and unleash, and you can still utalize reflexive and tactical plays to not die from it. You can dodge his shuriken and slash, you can dodge multiple shurikens and slashes, you can drag him to a sub-optimal position while he's ulting on you, you can play around his set-up.
Zed being a prominent pick likely has a lot more to do with Riot feeling he's got a ton of counter-play and allowing him to be a useful pick over anything else.
No counter-play is more pre-silence removal Talon. He instantly appears behind a target from 700 range away, disables all their abilities, items, and summoners, then turns invisible - becoming effectivly untargetable to all point-click mechanics and auto-attacks.
All you can do is not get within 700 range of him, then all you can do is move once he attacked.
So - pretty sure it's the exact opposite of:
I think the real reason why no counterplay assassins are so good atm
The key quality of champions like
and
is more they do offer reasonable reflexive/tactical counter-play options, so Riot doesn't feel obligated to send them to Evelynn tier. Several assassins are set up in such a way they offer no reflexive/tactical counter-play and are only countered by wide-reaching strategies (counter-build, counter-pick, team-fight formation), so as such Riot nerffed them to a point where it's a total crap-shot if they can actually kill someone when they jump on them.
Usually the "balance" of such champions is their lanning phase is awful and they have no solid means of CSing, so the counter-play with them is more preventing them from farming so they can never get to a 100%-->0% point, and unfortunatly most of those assassins either do nothing or jump on someone and hope for the best: making the unreliable and pretty useless if they get behind.
Kat and Zed get to CS well and can do things when behind for having the potential to massively get screwed over mid-combo.
I agree with you though.
She's awful at CSing and is picked almost exclusively because she can 100%-->0% someone with essentially no warning.
limited counter-play is a pretty solid advantage, especially in the hands of a skilled player that can really abuse it. At least she doesn't silence her foes any longer and a double-chain requires some time to fully activate.