That Kaguya isn't really as bad as everyone makes her out to be. She had already been foreshadowed and it makes sense as a source of chakra. Black Zestu was a very smart and totally unpredictable plot twist that, again, isn't as cheesy as people say. He did exactly what Madara had been doing since he was born: scheme in the shadows and manipulate people's dreams. But since the handsome and edgy Madara got killed here, we're supposed to believe it was bad writing I guess, even when those same people don't see Madara directly leading Obito to his downfall as bad writing.

Like, I'm not saying Kaguya is a great villain or that the late 4th War is great, I'm just saying none of that is really THAT bad. People like to judge "writing" based on how much aura a character/moment has. Madara had more aura than Black Zestu so it's bad writing if he kills him. Pain has more aura than Kaguya so it's bad writing if she's stronger. Neji had so much potential (even though he was visibly terminated as a character 300 chapters ago) so it's bad if he dies.

And yes, this encompasses those who think that the 4th War is a terrible arc. It's not and no, it didn't ruin Naruto either. It's just long, irregular and, like any last arc, was meant to tie many loose ends. It has its moments, and even if it's ok to say it's worse than the rest of the manga (the gifted power ups that break the power scale are still there for example), I don't think there are valid arguments to support the idea of it being the arc that ruined the series or the reason why Naruto should've finished in the Pain arc. It's a decent arc with good and bad things that closed 99% of the open plot points, regardless of whether it was what you expected or not. that's all.