The term “socialism” refers to an economic system in which human goods are removed from the market mechanism and currency exchange and are instead distributed based on need. To socialize an industry means to remove its products (whether medicine, education, housing, etc) from the market model and instead establish some means through which need is assessed and filled without the expectation of reciprocity. Socialism does not change who pays for necessary social services but replaces the very system of exchanging currency for goods entirely. A socialist viewpoint recognizes the impossibility of moral reform from within capitalism.
Removing products of an industry from the market model doesn't exactly remove the exchange. Even granting the impossibility of moral reform from within capitalism the extent to which Western socialists have no true Scotsman'd other real world cases of socialism off the table makes it hard to be certain that 1) socialism has ever existed or 2) can ever exist in the real world. It may be that there's a continuum between theoretical socialism and theoretical capitalism (and lately it seems that neither of these seems to have ever existed in the real world as its ideological partisans seem to have defined it) and that we have to find some rickety balance between extremities that is doomed to failure. But my impression is there is probably some other way to define socialism beyond this one.
Who pays for necessary social services hinges on a lot of definitions. Where does the money come from? Thatcher's quip about how you eventually run out of other people's money seems to run aground on the question of what money even is. I'm not entirely sure these days that when theories of the market were being formulated that an entirely data manipulated method of defining currency was what any of those people had in mind.
Just because mercantilism or contemporary capitalism manage to enslave people doesn't mean other systems don't have slave systems. Slavery seems to emerge regardless of the official economic labeling. I am inclined to agree with Ellul when he wrote that there will never be a collective ownership of the means of production. That premise is pure fiction. It hasn't happened and it will never happen.
Deboer makes an interesting assertion about how Marxism and communism are not anti-Enlightenment but the apotheosis of Enlightenment thought. Since the Marxist approach to history seems just as postmillennialist in its overall philosophy of history as, well, postmillennialist theonomistic dominionism, it's never clear to me these days why Marxists would think their view doesn't constitute a theological view just because they replace the eschatological apocalyptic revelation of a new world and dynamic of human relations with dialectical materialism rather than messianism in Isaianic terms. I suppose it's because I just finished reading George Steiner's In Bluebird's Castle but he pointed out that without the Abrahamic religious legacy of Jewish legal traditions, Christian ethical imperatives and the Judaic influence in socialist thought there's a whole strand of Western thought that vanishes. Steiner's case with respect to the Holocaust as a historical fulcrum, as best I can probably meagerly summarize it, was that the Holocaust was a predictable outworking of a tension between a previously pagan/polytheistic West and the inability of some ideologues within that Western tradition to reconcile themselves to the hybridized nature of what the West had become due to the influence of Abrahamic religious thought. Wiping out the Jews was a literalizing form of rejecting what some in the West viewed as the negative influence of Abrahamic religion. Now I'm sure there are plenty of people who reject Steiner's thesis or have alternatives.
But the older I get the more it seems that a weak point in Marxist thought has been the inability of Marxist thought to grapple with the necessarily religious debt it has to religion and not just any kind of religion, Abrahamic religion in particular. Even the atheistic streak is, potentially, indebted to a post-Abrahamic capacity of thought, to reject across the board the principalities and powers that claim divinity.
If capitalism is the human capacity to commodify itself that can never be eliminated without the end of the human race as we know it. The Soviet Union's history makes it hard for me to think that the way to explain all of that history is through a no true Scotsman claim that some of the Frankfurt school thinkers seemed to run with that that just wasn't real communism or socialism.
I have my doubts that capitalism and socialism can ever exist in the real world the way its advocates have been defining it.