Originally Posted by Kaling of Titans
Oh, so this is just something they left for HOW long now?
The tooltip is admittedly misleading. However, Riot has addressed this specific question to two points:
1) Champion actions that constitute as animations, like Ezreal's ultimate or, say, auto attacks, cannot be interrupted by anything. You know it's a channel if there's a bar that comes up, and it doesn't for his ult iirc.
2) The distinction between channel and animation is not a gimmick; it is an intended design feature. That is to say, they DO NOT WANT you to be able to interrupt Ezreal's ult or other moves like it.