If you don't want to play with a big spender, you can always seek an alliance, grow inside the capital, or migrate. There's plenty of options, I don't understand why everyone is seeking to destroy something big when they are still small. If it's the other way around then you should expect it in a P2W game.
Adding a cap on spending wouldn't solve the problem unless you're buying every cap as well, people will still complain that they're still unable to compete. What you all need is patience, if you are able to max out with the whale and get to his level, eventually you all will have to fight at an equal level. Though it will not be a one day thing for you since you're not spending on his level.
If you've been to PTR you'll be hyped to know the upcoming contents and might consider this as your next big game. Also, for a P2W game this is actually a much more generous game since there's plenty of ways to protect your resources and to grow by stealing carts while you're in the capital.