I don't think this is true. If my low cost attack drones just fly in, aiming to explode on your infrastructure or personnel, your defensive drones will have to

I don't think this is true. If my low cost attack drones just fly in, aiming to explode on your infrastructure or personnel, your defensive drones will have to be able to catch and kill small moving targets that may or may not have evasive or defensive weapons. I think swarms of cheap, possibly disposable, attack drones will be a real future threat.