If Aaron had not found Rick's group, where would they be now? Better off? Or overwhelmed by the herds? it didn't seem that they were being that self sufficient in Alexandria, hence the lawns versus what should have been gardens and fruit trees, more layers of barbed wire fencing and trenches outside, etc. (just what I think I would be doing for a safer encampment). So it is a double edge sword, they haven't brought good luck but maybe they kept worse things from happening?