Riven and Animation cancelling

This is not a complaint thread, I did NOT just lose to a Riven. Feel free to look. I'd ask you follow threw to the bottom.

Regardless the Riven players use of animation cancelling was... well... pretty questionable. I have seen it before, I don't exactly feel that it is "cheating", but since not all champs benefit from riven builds... I cant really say that any other champ can get away with it as much.

I bring this up because, the last Riven player was using it in a manner that looked like a Lag switch. Or at best, a space button to win.

I could clearly see that use of hydras and Shield cancelling the animation... but it was so fast, and without full on armor... it was 1-2 seconds for squishies on the team.

I'm talking, All 4 abilities, Hydra, and an autoattack pushing out 1.5k damage in about 2 seconds.

Why do I mention this?

I was playing rumble. I would Shoot my E out... right in her face. I would HEAR the noise. She would Q. No damage, no slow indicator. Just nothing. Riven would keep RUNNING like normal. My Harpoon, Hit... Riven Q one time... nothing.

So... Riot. What i'm getting at is this. Her kit, lets her cancel animation at WILL, throw in a hydra... they are popping it all, with her autoattack passive... in moments. How is that regarded as acceptable?