I suppose what I'm saying is, Goetia grants pity to Man, but it shouldn't be the human tendency to direct pity at others that gives rise to the Beast that is Goetia. "Pity" isn't the sin that humans have engaged in to bring about this result, as far as we know. Rather, what directly brought Goetia forth was human suffering and the desire for salvation. Losing to Goetia is "to give in to the pity of another," rather than "stagnating as a consequence of one's own pity." (Or maybe it's actually self-pity ... ?)
Desire for "Regression" and "Pleasure" more classically fit in with your theory, but the 4th Beast's "Comparison" is likewise not a complete match. Losing to him would be "giving in to comparison," but the outcome of such seems to be annihilation rather than stagnation.
EDIT:
Well, given that Demons are born from human desires, I guess the argument could be made that the pity involved here is ultimately the pity that humanity directs at itself ...
More metaphors. The Nasuverse loves its fantasies made physical, after all.
First, I'll argue that in all cases, giving in to the Beasts leads not to stagnation but to annihilation. It's called the Apoptosis of Man, after all. (And metaphorically speaking, stagnation
is annihilation anyway - annihilation of everything that makes life worth living and humanity worth preserving, at least as presented in, say, the world of Last Encore.) Losing to Goetia? Fundamentally misunderstanding us as he did, there is no guarantee that the new species would be at all close enough to humanity to be called the same. Tiamat? The Lahmu are nothing like us. And Kiara would simply "enlighten" us to pleasure, one by one, until there were nothing left.
Second, my argument is that rather than the causal chain being direct, humanity directly creating Goetia and Tiamat and Four, that humanity has created the Archetypes in the mode of failure states, and the Beasts are merely the beings who have been assigned their roles according to compatibility and symbolic resemblance.
Mundanely speaking, what does "succumbing to pity" look like? One or more First World nations, wealthy enough to want to help people and arrogant enough not to listen, tries to "help" - and ends up causing way more harm than good. I'm sure we can all come up with our own examples from recent history. Taken to such an extreme that the resulting catastrophe destroys all of humanity - perhaps through causing a nuclear crisis. In other words, a group of powerful individuals, allegedly benevolent, in a system designed to serve and save humanity, is the agent that dooms us. -- Goetia. His Pity is not our own pity, except insofar as he is a collection of demons, but he nevertheless plays the role of "our own pity come to destroy us."
"Succumbing to regression". Clinging so tightly to the past that we lose all ability to move forward. Modern innovations are discarded in favor of ancient favorites, modern ideas in favor of ancient traditions - in general, the people of the present in favor of the people of the past. The true agents of our destruction are simply ourselves - but if we were to imagine, like a poet or an artist might, an external face to this Sin, it would be precisely the figure of those doting ancestors, the ancient Mother to which we pay respects and whose refusal to let us leave the nest brings our death. -- Tiamat. There is no reasonable sense in which we created the mother of all the gods (except perhaps in one of the in-between states as the Age of Gods faded and the Age of Man began, in which Tiamat existed only because humans had faith in her), nor is her desire to embrace her children again at all directly causally related to our desire for Regression, but again, she nevertheless plays the role of "our devouring mother".
Kiara is probably the most obvious, so I'll mostly skip her, other than to note that in a certain twisted sense, she is certainly enlightening people to perfect ecstasy/nirvana...
Finally, the original point of contention "Comparison." Primate Murder can certainly be described in terms of "that which was born from competition between ourselves" - without that conflict he would never have taken form as Primate Murder - but more importantly, the metaphorical angle. Civilizational death by comparison is, bluntly, war. Nations growing more and more devoted to their posturing and their points of contention, putting aside all other factors, until they are competing without regard to their own citizens' safety or livelihoods. Nasu is not the first to imagine War as a savage beast, a cruel hound -
the dogs of war, indeed - nor do I think he will be the last. Primate Murder may not be, strictly speaking, our own comparison come back to haunt us except by his own supernatural mechanics, but he certainly well serves the role of "a metaphor for honor and conflict beyond all reason".
--- Completely off topic from the above, but it occurs to me that as far as we know, Primate Murder only exists in timelines where Altrouge raises him, right? AKA Tsukihime-ish timelines?
AKA the ones where Zepia calculated humanity's eventual doom, and all of Atlas followed? The one we were earlier theorizing might be an entire branch slated for removal as of the next QTL, hence irrevocably doomed?
It occurs to me that if the Human Order can't muster the Seven Grands, and there is similarly no ability to go back and "undo" him, defeating him before he is born in the shape of Four, then humanity might well be inevitably doomed to death-by-Beast in those timelines. The doomed-ness of Tsukihime might be entirely premised on Primate Murder's existence.