What's the point with that quite lackluster story in Endwalker?

[Sicno]

First, there the fact that the existence of Dynamis is not widely known at all. Emet and Hythlo, both scholars and experts in their own right, lack any knowledge of its existence until Hermes explains it to them. Venat as well didn’t know until we told her. It’s rational to conclude then that the vast vast majority of the Ancient world possess no knowledge of Dynamis.

They simply had no reason to pursue that knowledge at large because dynamis wasn't predominant in Etheyris and it's also weaker than aether, so there weren't "practical" applications. Hermes's was a personal interest in learning about other worlds to try to fill his existencial voids, so think of it as his "hobby". But that doesn't mean they weren't capable of conducting such research if they had REASON to. Like preventing their race and planet from being wiped out from existance.

Second, there’s the fact that as far as has been said entelechies have only been created in Elpis, with both the flower and Meteion hailing from there. Meteion as well is the most special between the two, being the only one possessed of a will or the ability to effect change in Dynamis.

The flowers may have been created there but they're present in other places too. Scarce, but not exclussive to Elpis. But I don't think this is as relevant as you think it is.

Third, even in Elpis the researchers we speak too lack any understanding of how Meteion or Dynamis functions.

And as I've mentioned before, Elpis is just one research facility. And one devoted to testing creations before letting them roam free. Its main purpose wasn't to design new creations inside it, but rather for everybody across the star to bring their creations and test them. Considering dynamis wasn't a practical avenue for them to explore it's not surprising that the only person with knowledge about it has it because of a hobby. But again, Elpis is JUST ONE RESEARCH FACILITY.


Having said all this, the "objective statements" you made afterwards crumble down except for the "other scholars" and Hythlodaeus parts. First one is explicitly stated in dialog, the 2nd can be inferred. Also, just because knowledge is scarce doesn't mean it's old, abandoned knowledge.