>>536983280
>why didn't they just delete than information from the irminsul.
They did.
Why that didn't work?
1. Enkanomiya is technically outside of Teyvat's Leyline.
2. "Before sun and moon" is technically derivative fiction work, like Nahida's fairy tale for Wandie, so it can't be altered by supernatural forces.
>why does everyone in natlan know about it
Not everyone knows about it though, they may have heard about it from another person then from shapeshifting lizard like Kukulkan (who canonically created Natlan's graffiti culture)
Phlogiston is a mean of storing and transferring knowledge IF you know how to use it.
Only the elites of the dragons knew how to do it, most of them were retards like humans too, hence their devolution into humans' pets/ cattle.