My admittedly limited understanding, is that in the Biblical setting, they practiced “open grazing”, which is best for small livestock, because instead of fencing them in and working to try to keep the ground continually producing what they need, you move them around to where what they need is growing, leaving the grazed ground to recover naturally. From what I can see of land in the Middle East, you don’t have lots of wide open meadows, full of all kinds of rich forage and grasses. It looks like a lot of barren land, with clumps of green growing here and there. Sheep that don’t follow the shepherd would be impossible to shepherd! They have to trust and follow. It is a great symbiotic relationship because the human helps the sheep find where to find good food, and the sheep supply materials for the shepherd.