I've never really felt Jinx was strong early game. She has some good range like Cait but lacks the escape and can be blown up pretty quick due to her squishiness. One gank from the jungler when she pushes into your tower normally means a dead Jinx unless someone messed up. She is VERY powerful late game but that is her design, weak defense, no escape abilities, lot of damage. In late game she should always be your team's focus which is why people often make protect the jinx team comps focused on protecting her very high damage output.