You are indeed on the wrong board, though I doubt
>>>/leftypol/ will be much more receptive to it, not least because it is not necessarily "leftist". Though you can try your luck there, you may have a better discussion (albeit at a much slower pace) at
>>>/dead/, one of the
secret unlisted boards where post-leftists, anti-ideological lefties, nihilists, and the like dwell. I am more than happy to discuss it further there. (I'm the schizonihilist anon who is now unable to post on /leftypol/ now that it has blocked all Tor nodes.)
But nonetheless, I will try to summarise my responses to these ideas:
Antinatalism as a position is rather orthogonal to leftism because it is a philosophical position born from a pessimistic existential contemplation of suffering as it relates to birth. It tends to be found among those more leftward due to some of the usual assumptions and framings that antinatalism takes, such as consent and atheism and materialist conceptions of existence, but it is not by any means an exclusively leftist perspective -- especially because it is more interested in existence and suffering than it is in liberation per se (though some take it in liberationist directions).
"Efilism" is honestly a meme pseudophilosophy originating from the pet self-theory of an amateur philosopher on YouTube. It attempts to describe and capture a particularly death-affirming antinatalist perspective that values death over life and inexistence over existence. The main problem I have with it is that the entire concept seems to be developed from a rather amateurish philosophical approach, especially in terms of its terminology, and seems to have zero engagement with more serious philosophy like Nietzsche's radical critiques of all death-affirming and passively nihilistic problematisations of suffering (of which "efilism" is just another death cult like Christianity and Buddhism).
While I think the concepts captured by what amateurs call "efilism" has some merit, if only as an example of a radically and holistically antinatalist perspective on the question of life, it needs rehabilitation from someone more sophisticated in philosophy. Even then, however, I think the entire perspective is fatally flawed and philosophically bankrupt because it fundamentally functions as merely an atheistic and secular form of death cultism, only basically distinguishable from Christianity or Buddhism by its radically pessimistic and materialist antinatalism. Additionally, I frankly find the term itself to be rather juvenile. If "efilism" is to be taken more seriously outside of niche amateur online antinatalist and philosophy circles, it needs better naming, such as "radical antinatalism" or "thanatism" or even "mortalism"; and it needs some serious development into a philosophy that provides a coherent and persuasive response to Nietzsche's life-affirming active nihilism and to the paradise engineering technohedonism of philosophers like David Pearce. I don't think it can, but that is the challenge it faces.
Regarding the relation between "efilism" and leftism, it inherits whatever association it has from its antinatalist parent, though I suspect "efilism" is more amenable to radically reactionary perspectives than antinatalism tends to be, in part because it is itself a radically reactionary response to the existence of life.
Utilitarianism is a whole other bag of worms with a complex relationship to leftism and politics, and all I can say at a general summary level is that it is an approach to utility, happiness, and suffering which seeks to optimise and economise existence toward the former two and (usually) against the latter, but in doing so instrumentalises all existence and tends to privileges death over life in its attempts at accounting for possible futures within present conditions. It is fundamentally flawed in that sense and many more, though as a
hermeneutical method it may still have its place when subsumed within a larger ethic (even a nihilist one).
Considering how each interact with each other is a far more complex analysis that demands even more text than I have already typed thus far (when this was intended to be brief), so I will refrain from doing so, except briefly thus: "efilism" is
at best a radically death-affirming form of amateur antinatalism that seems to lack the philosophical engagement, nuance, and sophistication of its antinatalist parent; whereas both "efilism" and antinatalism are usually approached within a utilitarian framework that prioritises suffering/disutility over pleasure/utility, yet can operate outside those frames.
If you want to discuss this further, I recommend going to
>>>/dead/619 or creating your own thread there. If you go to /leftypol/, I will be unable to join you and caution that you will probably not get a satisfying response. Lastly,
>>>/edu/ is another option, though that board is more a general space for serious discussion and I have yet to frequent there.