What logic are you using? They fought because there was disagreement, and she wanted the fruit for herself. That passage is pretty clear.
The problem is nothing says Kaguya didn't possess all those powers before hand except IT and dimension shifting?
We know how Ashbone works, if she had used Ashbone to wreck Ishiki's body, the only destructive jutsu she has shown, he would be dust. That means she has other offensive jutsu outside of Ashbone.
The old lore has been thrown into the dustbin, by this second rate writer. She negged Ishiki, then went onto eat the fruit and save the world. That's how I read it, and the order of events are displayed.