W is her passive amplifier which requires support input isn't it??? therefore it is very conditional, and if she's with a melee support (typical combo) then they often are not landing hits as often, plus it has a cool down.
Kalista is most dangerous late game with het nuts AS, before then her mobility can be handled by most other mobile champs, but once she maxes out, she can out manouvre even some dash and blinking champs. So the loss of damage in these scenarios still apply here as I explained
and the point with Kalista being melted once you do hit her, doesn't apply equally to the other adc's, as I said, once you get close, say with Leona or taric, you can burst her (with non 100-0 champs) quite easily, compared to other champs that can actually stay in the fight even if you corner them, like Graves and Draven won't immediately drop just because you "get into range"
If I use Maokai for example, I can close in on Kalista and rip her apart, but the time she escapes my CC, an ally will finish her off If I can't. (though she often kites to the point I can't even W, but it depends on situation)
On the other hand, when I go on Vayne or Draven, they can turn it around on me, stopping me from landing my full combo, so when an ally arrives, he they often get bursted down anyway, or I've even died to a fed Vayne in like 2 seconds, kalista, no matter how fed has never shut down my maokai that fast, cause Vayne stacks damage faster and has self defence, Kalista ONLY has kiting, meaning if you bypass it, you can melt her EASIER than other adc's That was the point I was making and I believe the point the previous post was making too (just without the explanation)
A similar comparison can be made about other squishy champs
A non tanky lulu can slow and speed buff herself all day, same with nami and kinda with jannah but she got nerf'd. If you bypass these skills you can burst them pretty easy, right? Wrong, they have a variety of skills for emergancy use, mostly Ultimates, but also other CC that can keep them safe "just in case" and allies can come save them. Champs like Soraka and Zyra not so much, if she fails to root you, she is probably dead before her ulti even triggers.
Both types are squishy and can be bursted, but while one is generally about getting into range (like with Kalista) others require prerequisites like a stun or knock up or silence (like lulu and jannah) or chances are, going in on them is suicide, since you will take the wrath of the rest of their team. I have played lulu like a fizz, diving right into the enemy, avoiding all their attacks, supporting my assassins as much as my tanks and adc, but as soon as someone drops a silence on me I am dead lol, Can do it with jannah too, but with nami I typically stay back cause her spells are slower, but the point is, just because you're squishy, doesn't mean you're easy to kill, and Kalista is very easy to kill
other adc's off the top of my head, MF (though she does have that burst), Jynx, Twitch, hence they rely on their other mechanics, allies and positioning to appear OP, but if you know how to get to them, they die much faster than Vayne, Draven or even esreal and ashe (but ashe needs her ultimate)