Not sure why you're getting down voted but this does seem like the key point. There obviously is a major challenge in avoiding conspiratorial nonsense in societies with strong freedom of speech, but in this example we have China facing something similar.

Note the reason of this conspiracy: the founder of Tang dynasty is not of pure Han Chinese ethnicity. In the grand scheme, this is just part of the rise of Han nationalism in recent years, which had its roots in the nationalism rhetorics adopted by the Chinese state under Xi.

I'm sure you can see the parallels of this in the United States and Europe.