Nightdiamond
Garak's wording in 'Rocks and shoals' was pretty clear in establishing that the Obsidian order was only renamed CIB AKA the order was not destroyed, it was as powerful as advertised, etc.
As for the founders, they almost certainly blamed ALL the cardassians for the Omarion nebula.
Consider:
In ds9:'The quickening', the founders condemned an entire species to die slowly, continuously of a biological weapon just because some of said species (the leaders from 200 years ago, all dead since long ago) had the nerve to defy the dominion.
What the cardassians did at Omarion nebula was far FAR worse - attempted genocide of the entire founder species, an unforgivable affront to the dominion.
If the dominion had won the war, the cardassians (all of them - not just the Obsisian order/CIB) would almost certainly have been dead the next day.
Until then, the founders were cynically squeezing dry the cardassians, getting all they could out of this 'resource'.
The fact that Dukat (who made the alliance with the dominion) and the rest of the cardassian people (who received the dominion with open arms) did not realise this fact is a testament to the level of indoctrination present throughout cardassian society 'Cardassia shall become the dominant power in the galaxy'.
True, but history has examples of huge armies being defeated or even wiped out, by much smaller armies.
In this regard, the cardassians have a negative record - they were driven off Bajor by rag-tag groups of freedom-fighters.
Now this one is in dispute. Some episodes say the withdrawal was a political decision. Depending on who you ask of course.
The withdrawal may well have been a political decision.
This merely means the cardassians could no longer afford to spend the resources needed to keep the bajoran system under control.
It also means the cardassians were unable to bring under control the bajoran resistance even after decades, despite overwhelming military superiority/total political control/etc.
A poor showing for the cardassians.
In general, whenever the situation required more than brute force, the cardassians consistently failed to deliver.