That would be because it's not a word used by the general public. It's a men's rights movement offshoot. If you see someone use it seriously, it's a dead giveaway of where they're coming from.
I get taking time off from relationships. I get feeling hurt. But to conclude from that that all women should be shunned, and you should never have any more relationships, is a bit extreme.
I guess I'll have to file this away with other delusional movements of the modern era.
I've been to Catholic monasteries in the US, plenty of women around most of them. Either working in the gift shops, volunteering with tasks needed around the monastery (often, the monks are aging and needing more help these days than in earlier eras). A totally cloistered existence is possible, but you're making a major sacrifice. Without a religious motivation I'm having a hard time imagining anyone making that commitment.
As I understand, even the religious groups (including Catholic cloistered religious, which as you note most orders are not) that take isolation to more extreme levels -- of both genders -- tend to do a lot of work to filter out people whose motivations are not religious, so I don't think that a religious motivation is all that essential to choosing such a lifestyle (the typical non-religious motivations may turn out to usually be insufficient to staying with that choice, though...)
Voluntarily celibacy and, especially, voluntary complete isolation from women have often been sold by organized groups with justifications that incorporate misogyny, so "organized misogyny" and "voluntary celibacy", while distinct, aren't completely independent.
So, I don't think MGOTW is, even to the extent that it combines these things, particularly novel.
It's creepy as fuck.
(also, it's seriously racist: I've had Asian female friends my entire life, and none of them are "submissive" or "traditional"... I can't imagine any of them putting up with that shit)
If you are reading about MGTOW then most probably you are reading a very slanted view of them by people who don't like to here that men are suffering. MGTOWs don't hate women nor they consider feminists as enemies. It is very much a political movement and hence gets shitted upon by political feminism. Not a surprise there. But to listen to ignorant people talking as an expert because they read something written by equally ignorant people with malicious intent is mostly funny, until you realist the very high number of male suicides. As I said earlier, if gender were reversed we wouldn't be having this conversation.
...a very good question, given that all the links on google for the phrase "theory of eulogy" lead back to this comment thread.
I think its something that it is very common for people to go through as a phase (and, also, the gender-reversed mirror image is common as this), particularly in young adulthood, and its also a thing that historically very common to have groups advocate as a lifestyle (usually incorporating a very negative image of women as part of its justification) -- but to the extent a gender-reversed form is pushed by powerful groups as a lifestyle advocated to women, it is also, if it incorporates a negative view of one gender, with a negative view of women.
Isn't this why we have the term: Eunuch