A parallel is a comparison of things that are similar or analogous to others,these aren't parallels they're convoluted and fabricated thoughts that lack in compactness while forcibly interchanged between subjects: from the brain(target of mental illness) to magic.
This would be a demonstration of you ignorring the elements actually being raised, yes.
Abominations are made through a subtle manipulation that can last even for years it isn't a natural process.
It's as natural as any other two-party arrangement, and requires no external catalyst. Abominations can occur wittingly, unwittingly, after years of stress, or in a moment's decision.
Abominationhood requires no third parties, no catalyst, no requisite materials, no rituals, and not even prior intent. It's more natural than arms and armor.
Demon carriers are less dangerous than abominations on the term being used because they don't possess the same magical raw power?
And because they happen far less frequently, because they barely happen at all.
Danger is a measure of both commonality and severity. Something that is both less common and less severe is less dangerous.
It's an oversimplification that put the emphasis solely on the mage and that disregard the hierarchy that exists within the spirits.
The heirarchy within the spirits is irrelevant to the management of the mundane order of affairs because the spirit heirarchy does not exist within the realm of the mundane.
Emphasis is put on the mages of Thedas on this side of the veil because no one is able to conquer and control the hierarchies of spirits on the far side of the vale. Focusing on what is actually in your ability to affect is neither an oversimplification or disregard.
A Revenant is more powerful than an abomination which was created from a rage or sloth demon because their spiritual hierarchy is superior.
A Revenant is a Pride demon possession- the equivalent abomination to be measured against a Pride abomination.
Which clearly work on the assumptions that most of the theodosian folks is well documented about history and magic and that their fear of magic comes from a well informed and deep study of the subject.
I don't think it's the case here since most of them are uneducated peasants.
If they were uneducated, they wouldn't know to fear magic they hadn't experienced themselves.
If we want to address Andrastian doctrine, though, the standard of judgement would be on the people who create it- who aren't the uneducated peasants, but the educated clerics, nobles, and scholars, and even mages who come together to understand the history and practical risks and applications of magic in Thedas. We would have to judge the on the historical validity of the religious claims- which include genocidal plague-carriers, ongoing human sacrifice, and the occasional outbreak of homicidal insanity with casualties far beyond any equivalent mundane executor.
Sadly, all three of these things are available in the Dragon Age itself, and that's living history.