Not the person you replied to, but here's my take on your confusions:
> I'm unsure of what "privatizing public spaces for socialization" is supposed to mean, or why it would be bad.
I think they were referring to the movement away from communal spaces and communally owned spaces, especially ones which contribute to socialization/enculturation. Things like parks, libraries, schools, which are for people and of people, but which increasingly are not by people.
> After all, a private property owner may extend nonpossessory or usufructory rights to usage of their land, which would make it perfectly viable for social gatherings without being necessarily more exclusionary than a commons or public ownership.
There's a difference between being a tenant on someone else's charity land and being a member of a community, and although I don't really have the expertise, time, or space to go into it, I imagine it involves a sense of belonging and ownership and community, that sort of thing.
> The promotion of the nuclear family model is an organic result of prosperity, which enables its existence to thrive.
This is true, and we've seen people moving back in with their parents on graduation now that the economy is weaker. This being true doesn't preclude there being a narrative that might eg take ideals like Independence and Self-Determination and turn them into a social impetus to form weaker bonds with extended family. I personally think it has a lot to do with our physical mobility increasing faster than our ability to maintain meaningful connections long-distance, but who knows.
> Same with beauty standards.
This has been problematic for generations and there's a lot of literature out there. I think that waving away the effects of image crafting on the psyche of young and impressionable folks in pursuit of profit is wrong of you, and you should consider re-evaluating this stance.
> I also fail to see how "promoting exotic vacations and recreational activities" is bad.
I mostly agree, except in the sense that people are maybe being sold a bad cure for an ailment they might not have had, spending money they don't have, perpetuating the problems that caused them to want to escape in the first place. Again, just for example.
For the last sentence, here's my interpretation: Markets are flawed because the actors in them are not rational or well-informed (which is often an axiom of whatever model one chooses to use), and because the actions available to them are dictated by those currently on top[1]. I think OP was referring to the way that boiling human interaction down to market interactions - trusting the Market to be a true and somehow just proxy for Everything - is causing problems; that is, trusting markets (alone) to meet human needs is failing.
Hope this helps.
1. For instance, violence or overt threats of violence in pursuit of gain is considered to be taboo in markets (that I know of), since those who have goods or the means to produce them generally want to keep that relative power over those who do not. We see alternative, or extra-market action in eg ecoterrorism, where someone whose needs or desires are not being met, and who have no in-market recourse, resort to destruction in order to reduce profitability of hummers or whatever.