It's obvious that this is beneficial for the population, but is it (typically) beneficial for an individual?
Probably, selfish individuals would only want to try this if they're already well-fed, or if they're confident that there will be some food left over if they don't find any of their own.
So, for the benefit of the population, we should probably make sure that everyone is well-fed, so that everyone feels confident to go and find new sources of food :)