In small scale you are 100% right. Leave them to their natural behavior and they are perfectly able to eat the right amount of grass, insects and small rodents

In small scale you are 100% right. Leave them to their natural behavior and they are perfectly able to eat the right amount of grass, insects and small rodents that their egg and meat will taste great (some support grains is needed). Force them to eat only the cheapest animal feed and pick breeds that wouldn't survive in the wild, and the resulting egg and meat will have a distinct worse taste. For small scale, chickens really are one of the most useful and easiest going animals one can have, and it is one of the things I miss living in a city.