I'm saying if someone picks Kassadin to counter you when you pick Ahri ... you're looking at a steeper hill than that Kassadin is.
Wasn't that my original point? It's not an impossible lane. There's times where you can do things but you're not looking at a situation of literally being unable to do anything. Where you have no hope from Level 1 and no chance at any point during the game.
Kassadin wouldn't have been my go to example for this "HARD COUNTER PLS HELP" to be honest. It's lopsided post-6, sure, but 1-6 is just as lopsided in the other direction. I was half expecting to have to explain what to do vs an Akali (though it's a similar situation so I dunno) or Swain, honestly.
Sure pre-6 is easy against Kassadin. Kassadin shines mid-late game.
And that's why the entire emphasis for EVERYONE vs Kassadin is to shut down his 1-6. If he dies early or doesn't get any cs then you need to use that advantageous situation to deal with his better 6+.
Any good Kassadin post 6 will come in with his full combo. You're silenced, you're slowed and he's retreating away scott free.
How good are we talking about? Kassadin's R has an animation and it's relatively predictable if you're familiar with how Kassadin wants to go in. It's not impossible (or that hard, truth be told) to Charm the ult in.
Now, a good Kassadin will vary his engages and approaches but there's still a delay window to get a Charm in before the Q can be cast. But a good Ahri still has options.