Not trying to target Cat just using the video to show the theory
It was a long while back when people were just starting to realize that Yae and Ei weren't who we were led to believe. Of course for many the justification for the theory was that Ei made a statue that looked like Yae and that was pretty much it.
So this counter theory goes that there's a book
and in it we learn from a conversation between Yae and Urakusai that Yae wasn't even born yet when Kitsune Saiguu left during the Cataclysm. That must mean she was younger than 500 years so she couldn't be the Archon just by her age.
But now we know this:
Funny the stuff people tell you when you're a fetus isn't it? So much nonsense that woman spoke while Yae was still a twinkle in her father's eye..... 
Ok so my real point for bringing this up is to be careful when theorycrafting. Never use just 1 piece of evidence to justify your idea. Also the books likely require interpretation so you shouldn't take them word for word.
This is why I feel that for example the Seven Sovereigns is just another name for the Seven Archons and we still need more details on what the Byakuyakoku books are really saying. There's plenty of information that tell the history of Teyvat from its earliest point and they only talk about the Archons. Only Byakuyakoku suddenly brings up the idea of dragon lords. And just think about it. Does it make sense that we suddenly have another 7 nations with humans under the care of 7 sovereign dragon lords that predate the 7 nations with humans under the care of 7 Archons? What happened to them? Why is there no trace of them at all but we see tons of ruins for everything else that supposedly came before the current 7 nations like the single human civilization period of Enkanomiya or the ancient human period of Khaenri'ah and Sal Vindagnyr? (not saying MiHoYo couldn't make it happen but as of right now there's not enough to justify it)
We're also about to head into Sumeru where I theorize that because of the whole raving scholars and knowledge as a currency thing that we'll get a ton more information but almost all of it will be nonsense. So if we take everything word for word that'll be a very weird story. I can't wait to hear how Celestia is really a spaghetti monster who traveled from Narnia in 500BC to the New Roman Republic of 2405AR (that's AR for "after reconstitution") using the sacred hot tub time machine and then discovered the secret sauce of McDonald's which allowed them to destroy Khaenri'ah by instituting the Jazz Hands Protocol and brainwashing the Archons with Tricolor Dango until Lumine discovered the plot but then the Sustainer used cubism on her and her brother which is actually the false sky we heard about that one time.
It's all Picasso's fault! 
-ahem- Also yes I have a theory how it makes sense for Yae to both talk about having conversations with Kitsune Saiguu but not being born yet when she left. Actually if you guys really pay attention to my stuff I already mentioned it. 
And I'll get into it again later.
Tips and Tricks from a Super Casual Genshin f2p
