I used to believe that too but not all free range soil is created equal. There still needs to be appropriately sized sharp stones present.
I started providing grit for my free range birds and they devour it like they haven't had any.
It is cheap so I don't scrimp and it lasts a long time. A 50# bag is somewhere around $10 and will last 50 free range birds about a year, confined birds half that.
I keep bags of #1 chick grit, #2 adolescent grit and #3 adult grit on hand all the time. I start the chicks the first week with the grit sprinkled on their food and in a separate container or just sprinkled on the floor for about 5 weeks till I switch them to #2 for a couple months then to #3. Grit too small will pass right through the gizzard without lodging there and serves no purpose. Even if they are only eating chicken feed, the grit helps their gizzard develop.