but then if you had all their balls they would get zero points and you would get zero points

Did any of you notice that there are two ball chutes on each side of the field. You can block one, but you would have a hard time blocking both.

Good observation.

I have a feeling that this will be illegal soon - FIRST will probably make this action illegal in one of the rules updates. In any case, it’s not at all good for your ranking - your scores would be low, and you’d plummet in the case of ties.