The argument goes (or one of them anyway) that rights are well and good but largely meaningless if you don't have the ability to exercise them. Like you can't exercise your right to life if you are dead and you can't exercise your right to liberty if your life is being threatened (explicitly or implicitly) they are not substantive.
So if your life and wellbeing is being (implicitly) threatened by impending eviction from ones home and subsequent starvation if one does not "make a living" then one may be forced into taking whatever job is available no matter how dirty, difficult, dangerous, unfulfilling, no matter how tedious and no matter what end of life security (if any) it offers.
That means that you might have a group of working poor who are paid so little and forced to work such long hours and is so busy maintaining their paycheck to paycheck survival that they simply do not have time for liberty or the pursuit of happiness.
One suggested solution to this is a universal basic income. This is the idea that either everyone would receive an amount of money sufficient to maintain their lives and wellbeing (home, food, medicine etc) or that these considerations would simply be supplied directly.
This has the advantage of being a solution that does not require that we demonetize (do away with exchange mediums) and therefore one requiring less change to existing infrastructure than a purely and perfectly socialist system (in as much as such a thing is feasible).
Now this discussion is not about the relative benefits or disadvantages of socialism but only about the effects (benefits or disadvantages) of instituting some form of U.B.I. as a part of our free market system (just to put an emphasis on free) and what such a system might potentially look like/operate.