Great, so that means they aren’t mining minerals and you are.
This means the longer you stop them from mining, the more likely you are to get ahead in workers. It’s damage one way or another. So it goes from how many workers you kill to how long you can keep them away from the minerals.
So on one hand: You kill workers.
On the other hand: You stop their mining and use that advantage to get ahead economically. Thus allowing the advantage of a better army later if they don’t quit first.