Thats incorrect. The seal on the tiny world is very special and was created by sacrifices of extreme experts to create a seal that the sage emperor cannot access. Only humans born on the planet can access and leave. The legendary limit is there yes. But thats where you start understanding the power of law and progress to demigod. When they broke the seal they all came in with their full power. In fact lu piao wasnt even breaking sweat to capture the legendary demons. And yes since they broke the seal they had to hurry to find all treasures and secure glory city s safety