this whole "leaving the nest" thing is a creation of bourgeois capitalism.
as we live in ubiquitous capitalism, it's easy to understand why self-identified leftists may not realize that they're propping up capitalist ideology by criticizing people who stay with their families past a certain age. but, a thorough deconstruction of capitalism would have to address this as an issue.
why do we insist that kids move away from their parents, using the model of birds? are we not primates, rather than birds? do primates not live in kin groups? do they not practice kin selection? and, what does the individual gain by moving away from their family?
the reason we insist that kids move away from their parents is that it drives the housing market and props up the rentier class; it's a way to maximize the extraction of rent, to the benefit of the property owners and the expense of workers. that's how capitalism works, kids. yet, we are certainly primates, and primates certainly practice kin selection, so this is acting against our nature and our evolutionary impulses. so, why do we buy into it?
it is the answer to the last question that the issue really pivots around, and it depends on whether the specific individual gets along with their family or not. somebody with a very strong, close-knit family relationship would probably not benefit from moving away from home at all, whereas somebody that sees the world substantively different from their parents potentially would. now, if we move very far into the leftist project, we get to the point where we collectivize housing outright, and the debate kind of evaporates. call it a kibbutz. cite plato. whatever. but, the family as a feudal concept breaks down when you eliminate the property relationship, and that does need to be the end goal. yet, even then, you don't necessarily physically move away from your family so much as you allow for people with more distant biological relationships to take on roles that we currently delegate to close family members; it's less a physical separation and more of an emotional separation. in the mean time, if somebody can get along with their family then it would clearly make financial sense for them to maximize their resources by staying at home as long as they can, pooling their resources into the existing family finances (house, car) rather than into a new one and eventually inheriting something that's been paid for rather than buying something new. that's not ideological; that's logical. and, that is of course the trick of the social coercion - don't inherit your folks' house. buy a new one. then, the bank wins and everybody else loses.
as an anarchist, i broadly reject the idea that i have any right to tell somebody how to live. as my interests lay in art, and i consider paying for shelter to be an annoying burden, i would have rather stayed with my parents until the end; my parents did not care about my art, but rather expected me to go to school and get a job and start a family, things i did not actually want, so i was forced to leave against my will and go out and carry through with this contrived exercise in capitalism that i consider to be a waste of existence. i ended up working part time jobs, just enough to pay the rent, mostly avoiding any kind of social life and focusing as much energy as i could into my art. there was a fundamental breakdown in understanding, there - they didn't understand why i didn't want a good job, why i didn't want a car, why i wasn't interested in starting a family and why i "wasted" so much of my time on art and writing, and i didn't understand why they didn't just fucking support me in what i told them i actually wanted. so, we made no sense to each other. but, if i could have found a kind of benefactor, which is how they did it in the enlightenment, i would have happily moved into
their basement. in the end, that's kind of what happened - i live in somebody else's basement, and pay rent with government subsidies. and, i focus on what i care about, and spurn what i don't.
i would have rather just stayed home, and if i had just stayed home then i'd have a lot more work done, too.
if other people have families that they're able to get along with better, then power to them. they have something i don't. and, i have no interest in criticizing them for that or trying to coerce them back into capitalist orthodoxy.