Things that are outside of fate tend to be direct extensions of Primordial power. Alchemicals are outside of fate because they're pretty closely tied to Autochthon. Infernals are outside of fate because they're running on Primordial Charms.
Second and third circle demons are outside of fate because they're extensions of a Primordial. First circle demons aren't because even though they're not native to fate, they're not big enough not to get ensnared by it the moment they come into contact with it.
"Outside of fate" isn't a matter of being mystically potent; it's a matter of being a specific type of mystically potent. If you're powered in such a way that you maintain your own causality, i.e. run on the same sort of OS as the makers of the universe, you're outside fate. Otherwise you aren't.
Abyssals aren't running on Neverborn power the same way Infernals are running on Yozi power or Alchemicals are running on Autochthonian power. They're inverted Solars. They're mystically puissant, but not in a way that leads to them naturally tearing through the fabric of the Loom whenever they move around. They actually have to manually direct their occult might to that end in order to be like that. It's well within their power, but they have to put their wills to it.
(If any of you want to assert that this doesn't make sense, then I apologize for not explaining it well enough that it does, but trust me, this is the reason.)