Someone please explain to me how this is balanced...

Sejuani was roaming just farming and roaming normally. Around 20 minutes she obtained a LT. After that she was able to solo pretty much everyone. Every lane held their own fine. No one died from over extending, positioning, I had high hopes for the game. At the end she was able to solo me, Pantheon, and Udyr. Now, some explain to me how a build, such as Sejuanis build here where she only acquired ONE damage item which was LT, out damage a full damage Kayle by more than 10,000. And no, we had brains and everyone played well, we just couldn't do ANYTHING while she was around. I'm trying to prove a legitimate point here. A few patches ago Riot nearly doubled Sejuanis damage. A reason she has the 2nd highest win rate in the game.