Telling you to 'just CC the fucker' is telling you a form of countering a champion, it's just not as well worded as it should be.
Like if someone said "Just CC Kat," well if your team wasn't in range to follow up, what did you just do? Annoy her.
Now, if someone tells you "Just CC Kat when she ults, this stops most if her damage, and now she's in the middle of your team," now you've been told how to play against her.
Same thing for Zed. CCing during his ult. Depending on the length, it removes most of the damage he could cause and let's you walk/limp away.
For Kalista, it'd be more "She has a really exploitable early game. She cannot cancel her AA, and as a result will stand still for about a good deal of time. As such, you needs to poke/AA/initate when she does this. One or two early punishes will cause most bad Kalistas to back off, delaying her annoying late game. Targeted CC also helps loads."
So yes, CC is a counter to every champion, but it is a reliable argument when you tell people how and when to do it, not just to do it.