One of the first MMOs ever created had a feature that was beyond their time. That game featured a fully-fledged ecosystem, in which herbivore animals would feed on plants and predators would feed on them.
It ended up being a complete waste of resources, as the players killed the animals faster than they spawned. The average animal lasted so little that the devs ended up taking the code for the ecosystem out of the game in a subsequent patch.
The devs of Hyperborea wanted the game to have that ecosystem and even more detail than that. With that goal, they set up some guardrails so players wouldn't overhunt.
First, they created a distinction between animal and monster. Animals don't give too many drops, and they are all useless for any player beyond the very early game. Even for feeding NPCs, it was more efficient to raise domesticated animals.
