Then she'd be too powerful and it would ruin/change the whole balance of the game.
"she"
?
then it would be a rook
because it can't, that's the way the game was created
If international chess has a piece such as "pao" (from Chinese chess), where it moves normally like a rook but can only capture an opponent's piece by jumping over any piece, theories would become more complex.
too difficult
Then she'd be too powerful and it would ruin/change the whole balance of the game.