I think I know what Fandaniel meant by did Emet Selch find a way to...

Zenos and Fordola don't just have a man made echo they also have a man made blessing of light. After all we learn those two things are separate. And that it's the blessing of light that allows us to fight primals. Why else would sending Fordola fight primals work? Or Zenos fusing himself with Shinriyu? Otherwise the only thing that would have saved him from fusing with a primal is being the grandson of an unsundered. How did this realization not pop up during 6.0 talks? I only came to it after playing back somethings that was stated about what must sort of happen in DRU in my head. Where Thoridan is only able to keep his form after being spared is due to having absorbed so much aether from other sources. And how after we defeat him in the MSQ he just dies and turns into aethrical dust particles is due to not having the blessing of light.