I know how to fight most champs. Doesn't mean that you're not sometimes first pick or pick before they pick? for ever Katarina counter, there's 10 champs who stomp on her counters.
Zed doesn't really have a counter anymore, so personally, I like to ban him.
And you can say "learn to fight them" all you want vs a Jinx. Her play isn't about whether you "know her or not." It's about whether your TEAM knows her or not. If she gets a single kill or assist, she's going to finish your entire team. That's how jinx works once she has
. After that, she has a massive move speed boost and overcapped attack speed hitting for 900 crits from 850 range, and there's literally no avoiding it, because it's 6 full seconds of 175% move speed boost (on a Jinx that's literally around 1,274 Move speed, and with overcapped attack speed that means she procs 2-3 attacks a SECOND when chasing while Excited!, and every kill renews her).
The only way to escape an Excited Jinx Mid - Late game is either somehow kill her through her life steal (unlikely) or to Flash over walls and hope your team doesn't reset her Excited while she's chasing in your direction.
When that's the only counterplay...... you really throw out the argument: know your champ.
Ofc, a Good Zed can Eraser her, but he might die in the process or almost die.
There's one reason Jinx was OP, and that was Warlord's Bloodlust proccing huge heals. It's back in Fleet Footwork, and now she can proc it far earlier in the game, faster, and about once every 2 seconds in late game.
Furthermore, Jinx is often getting Duskblade now, which means ward removal, and Armor penetrating ults.