100,000 congregations? No
1. There is not a big apostacy problem in the 3rd world.
2. Often letters are sent to specific congregations, circuits, districts, or branches.
3. They could use this to get a general idea of problem areas and use COs to do the leg work to fix the problem.
Im not saying this thread is not BS. Im just saying its not an insoluble problem to use this technique and that I wouldnt put it past them.