is bad because her kit makes you feel not like you got outplayed, but you got cheated by a design that was intentionally overloaded even by today's standards. Combined with the fact that all of her counters are very weak right now and you have a champion that essentially has no answer for anything she does.
is on the same level as
in the sense that, left unfocused, he can and will melt anyone he can auto attack like absolutely nothing. There's a composition called 'Protect the Kog'maw' for a very good reason. However, both Kog'maw and Jinx are very vulnerable to strong dives and can be killed within reason.
Vayne however, is very difficult to focus with a 2 second Tumble (And that's BASE Cooldown) which can essentially turn into Invisibility while using her Ultimate, her Condemn could push literally anyone except a
,
,
,
or
out of auto attack range which turns into a Stun if they collide with an object (and don't say anything about Positioning, you know as well as I do her Tumble could be use to turn your good positioning into a stun) Night Hunter feels absolutely ludicrous on a champion that already has good Mobility (I mean her MS is 330 but Tumble is 6-2 seconds, this is completely ignoring
, obligatory
or
, and MS Quints) and basically guarantees she will chase you down and kill you unless CCed, her Ultimate turns from a
to a
and then both of them combined (almost a
worth of damage)
This is, of course, all on top of her Silver Bolts which cannot be reasonably countered except by picking
and rushing a
(which just got nerfed, by the way) to slow her attack speed instead of being able to build Health to counter her True Damage or Resistances to counter her Percent Health Damage. There is no meaningful counterplay to it aside from 'CC the living hell out of her' but not every stun is Point-And-Click and considering she can dash more often than
I wish you luck in aiming any sort of skillshot on her.
At the time of her release, League of Legends needed a Tank Killer, someone who could kill the invincible
(At one point he was uncounterable, this simple fact leaves me baffled) but now League has plenty of them and we are now seeing champions like
and
who are considered top tier and even countering entire categories of champions. Then we look at Vayne and realize not only does she counter tanks, she's also extremely good at killing Squishies (because in truth her kit was designed to counter tanks but the actual numbers are aimed at giving her AD bonuses and flat True Damage, which is more efficient against squishy targets)
Basically, the fact is Jinx and Kog'maw are both very low-mobility with limited self-peel because they excel in teamfights and sieging. They have clearly defined strengths and weaknesses. If you dive them, they have a very hard time getting away and can be easily killed. Hell, Kog'maw has one of the worst laning phases of any ADC. Vayne lacks that distinct counterplay because everything that counters her has been nerfed so hard she can bully the bullies out of lane efficiently and after lane ends she's nearly impossible to catch unless she wants to catch you. It's a matter of Meaningful Counterplay of which we find lacking.