If your nontechnical neighbour's ISP calls and says "you're participating in a DDoS, will you please find out which device behind your NAT is sending the traffic and fix whatever the problem is", do you think your neighbour can fix it in five minutes?
They could, which mitigates the attack without locating the actual source (that is, your app) and leaves you free to use the same app again for another attack next week. Maybe even taking care to use a different subset of the devices where your app is installed.
