Power
It was incredibly rare for a single phenomenon to affect the entire universe. Although there were many who could cause such a thing if they consciously tried, none of them were stupid enough to try. Even a Dao Lord could not tolerate the attention of the entire universe. Or at least the realms which contained humanoid beings, which was still a pretty big portion of it.
That is why when exactly such a thing happened, many could not help but feel extremely curious. Many immortals, and even Dao Lords, of various races tried to peer into the secret of the figure.
Yet whether they used divinity, or looked into the laws, or touched upon the Dao, all of them gave them no feedback. It was as if a more powerful, more mysterious force had shrouded the truth.