Even in mid plat elo I just had a game where the game dragged on where we couldn't end and Jinx got her 5 items but couldn't carry just because we set her too behind where her team pretty much didn't have an ADC early. We took all barons, dragons, 3 inhibs and just let baron super minions end. It was also a perfect teamfight comp on her team with Amumu and Naut.

It was extremely easy to shut her down early/mid, especially with an Akali and Gnar who just jumped on her. The higher up the ladder you go, her weak early game and low self peel will just be taken advantage of more and the game will end before she makes any impact on it. I've been in this situation too many times and only pick Jinx against another scaling carry with little dive.

I believe she's stupidly broken in silver/gold simply because games tend to drag on and her weak points aren't exploited hard. Also they just want to teamfight where she's the strongest.