Did you uh. Actually watch the video?
Having played both I can say Aatrox has a vastly different play style.
Nope, didn't watch the video. But if a Riven player is making a guide to animation cancelling on Aatrox then there is definitely something wrong with Riot's gameplay "creativity"
You do know there's a bunch of champions with animation cancels, right?
Right, but it's almost a must on Riven. Plenty of other champions can do it, but it's never a necessary skill to learn. Except with Riven.
If you've don't learn the animation cancels of the champions you play you're gonna have a bad time.
Try playing renekton to max effectiveness without his cancels.
Also if you watch the video the biggest cancels are just with Tiamat. I wouldn't call the synergy between his abilities "cancels" because Riot clearly designed them that way.