Let's first remember I'm only discussing low level. I started this thread at maybe level 5 and they're level 8 now.I do not know very much about Extinction Curse. Are there monsters with frontal cone AOE or nasty auras at all? There is a significant amount of that in PFS.
By that I only mean to ask: are your monsters higher or lower level than that?
(I don't know which features you're referring to)
If your answer is "at all levels" then yes that's a difference, since I can't remember any monster with either of those. (Xulgath mages have Fireball prepared but that doesn't seem to fall into either of your categories)
If your answer isn't, maybe those features are inherently tied to higher levelled foes?