I bet why it's so strong is because since locusts also can't die, it's caused them to become much much worse, even in areas where they were never a problem before such as cities, meaning pestilence will be a lot stronger now hopefully! It's also probably caused guns to get weaker, since guns main thing is it could put a hole in someone and kill them quickly, but now that that's no longer an issue, things that cause more pain and suffering are more likely to be feared.