I believe this as well, especially after reading about the War of the First Council, that Vivic especially wanted Nerevar out of the way and layed the blame on House Dagoth.
In ESO we come across the Sixth House in the Forgotten Wastes, where one I think sees the truth of who betrayed who, Nevena Nirith - but what or who was the Statue she was assigned to - that her brother thought to have influenced her.
From her Journal:
What is known for sure then? is it that Sotha Sil, Almalexia and Vivic did use the tools of Kagrenac, which broke an oath they made to the Daedra Prince Azura, and Dagoth was left behind within the heart chamber of RedMountain - where the beating of the heart is still felt, and now in ESO's time stirrings of Dagoth are being felt - ones of the Dagoth blood line when touching an Ash Statue see a truth they wernt aware of.
and just wonders..
The Blight that would come, would it be similar in a sense that it is focused only on the Dunmer, similar to the change Azura cast on the Chimer in response to the breaking of an oath
The chimes that guarded the entrance in the Forgotten Wastes - are they of Daedric Dwemner or Chimer origin..
and is Dagoth, from where he has awaken able to send his thoughts to others through somesort of tonal communication..
and another thought, when the tools of Kagrenac were used by Sotha Sil, Almalexia and Vivic - did they spilt the heart taking what they thought would make them gods - the light maybe, leaving the dark of the heart which Dagoth might have absorbed.
In the Library of Andull the Librarian Bradyn states that the genealogies of the Great Houses date back to before the War of the First Council - only five are there and not of House Dagoth, - if this was before the War of the First Council, why would they not be. If their genealogy record was removed and the Chimer spirit that represented them banaished - I just question what was it that needs to remain hidden, and since the genealogies are written in a script that the Librarian has to deciper I don't think it ever to be known. I do think though that there was one written of House Dagoth and it was this that was revealed to Nevena Nirith which made her forsake her acceptance into the Tribunal Temple to join the Sixth House.
so other wonders/questions that come from reading this lore book:}
As Azura had Indoril Nerevar as her champion/avatar?, did the other two good Daedra that the Chimer followed, Boethiah and Mephala, have ones as well? Was Veloh - Boethiahs champion and could Dagoth have been this for Mephala maybe. Is/was Mephala the anticipation of Vivec, Azura the anticiption of Sotha Sil and Boethiah the Anticpition of Almalexia - What do Anticiptions in this sense mean - that they (Vivec, Almalexis and Sotha Sil) were prophesied/promised to become powerful like these Daedra? and decided maybe they no longer wished to?
Also from this lorebook, are the Velothi Prophecies that are mentioned known at all from any of the other games.
This Ritual Table of the Sixth house have letters in Daedric script I believe, as are the chimes in the Forgotten Wastes?. Do they both spell out Dagoth in Daedric script.