Better water quality to start and not all fish can be fed this way. Depends on the species but most don't eat every day in the wild so they actually get fat in our aquariums. Most fish that die in our aquariums of natural causes have pretty fatty livers which contibutes to their death. Just imagine the difference between a fish that has 10s of thousands of gallons to hunt/forage for its food over a fish in a few gallons having food dropped in every day to it....