Why does LoL hate luck?

So I started playing league in s4. I watched some older videos. Why is LoL getting rid of % stuff. With that I mean.. Well, old Yi. **15%** chance of second strike. Old Sion. **X%** chance to take **Y%** less damage from the next ability/basic attack(I don't remember that well). Jax had a **%** dodge chance. Why is Riot getting rid of things based on luck?
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