I went over the synopsis yes.
Ultimately its just that simple to me really, the blight hadn't even gotten into full swing yet you have people purport to it being the end of Thedas if action hadn't been taken.
Really?
The closest the Blight ever came to success was the first and that was just century after century of the ****, humanity persisted across Thedas, even as the dwaevens crumbled below.
This was a near extinction level event boyo.
That was 12 years of bullshit.
The First Blight had a massive Tevinter Empire across most of Thedas that had a coordinated defense against the Blight. It was apocalyptic, but for all its faults, a decaying Tevinter Empire could handle that kind of threat. As the Codex entries describe it, after the first few years, they settled into a war of attrition until they could figure out how to kill Dumat permanently.
The Fourth Blight had a massively divided Thedas failing to hold off the Blight. Antiva and much of the Free Marches were devastated. The Fifth Blight is the only one to never get into full swing. It's arguable whether the 'quick' death of Andoral was worth losing the griffons for future Blights, but they didn't know that when they made the spell.
The griffons, bolstered by the spell, were able to take down Andoral. Grey Wardens had taken huge losses, as had every other force. The Archdemon was the lynchpin of the Blight, and very, very hard to take down. The blood-craze made the most of limited numbers.