Starting from the Original God, Selling Mythical Beasts

After crossing the continent of Teyvat, I got a simple and crude system - the mythical beast cultivation system. The benefits are also good. You can copy the mythical beasts in the form of eggs for free, but they cannot be repeated. But... Why is it necessary to sign a life contract to hatch? Why do I have to slowly cultivate it myself after hatching it? Why do I have to be punished if something goes wrong? Wait, there seems to be no restriction that I can only do it by myself, why not open a shop? This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.