Have you ever played an RPG? Stat scaling is what causes this effect. Early in the game, damage is king and wizards/healers kind of useless. Tanks are irrelevant and just tanky brawlers who hit hard. No one uses support power and pure combo damage is the winner. Battles tend to be short and so simple that you can literally spam the Attack command.

But late game in RPGs the stat growth has diversified the characters. Now tanks hit for nothing but can take a cannon to the face. Healers are no longer useless but a vital element of your survival. Wizards drop atomic bombs on enemies and provide the majority of your damage. Battles are long and grueling with a single fatal mistake often spelling your demise.

We've moved past the "lol Lightning OP" stage and are getting into the midgame where stats have more of an effect. But arena is already in the end game where ninjas are at their full power and the meta is completely different.

Yeah. It just becomes more control focused. You're probably going to use Acupuncture and CC in your teams instead of just stacking damage.

Lightning's advantages are the leech buff, the condition immunity, the defense ignoring standards, the jutsu/combo disabler, Lightning's all about counters. No defense or opposition can stand up to Lightning's assault. It always finds a way through.

But that means to be effective it wants ridiculously high refinement. More so than other classes.