1. Islam does not condone the idea of going around begging so one could buy sacrificial animals for slaughter on behalf of others. This whole thing about animal sacrifice outside of Meccas is a fabricated ritual.
2. You can buy somebody a goat once a year, but how about the rest of the year? When people are starving for food raising milking animals makes more sense than having the luxury of eating meat once a year.
4. Things that stop illness and spread of diseases are 1. Quarantine, 2. Good Nutrition, 3. Personal Hygiene, and 4. Good Sanitation. You cannot ward off an epidemic or cure disease by praying and sacrificing lambs and goats. Please seek wisdom and guidance from the Holy Quran and stay away from following fabricated stories (Ahadiths).