I think we should call modern leftism “new communism” or “neo-communism”. It has other names, such as “social justice” or even “liberalism”, despite its profoundly unjust and illiberal views and actions. These labels hide the true nature of modern leftism: that it is just another version of communism.
I should be clear that I am referring to ideology, not to how society is organized. It is often said that real communism has never existed, and that is true. Real communism has never existed as a social system, because it is a utopian ideology that can’t exist in reality. However, communism has been very successful as an ideology.
Communism doesn’t work in reality because it is based on false assumptions about human nature and society. (Forget about whatever Marx said, because it really doesn’t matter.) Communism is based on the concept of altruism. Communism assumes an altruistic moral imperative: that individuals should work for the common good, not for their individual benefit. This moral assumption is much older and deeper than communism, of course. Communism projects this moral assumption onto human nature and society. It assumes that human beings are intrinsically altruistic, and that society can and should be based on altruism. In the ideal communist society, everyone works for the common good, without any need for incentives. Everyone gives according to his abilities, and everyone takes according to his needs, and everything works out.
The reality is that people are selfish. Selfishness is consistent with both competition and cooperation, but not with altruism. Society is based on cooperation: people working together for their mutual benefit.
Communism portrays cooperative relationships, such as marriage and employment, as exploitation. It demands that they be replaced with altruistic relationships. The inevitable result is not altruism, but conflict.
Old communism proposed that all individuals should be equal, rather than some being rich and others poor. The communists viewed disparities of wealth between individuals as unjust. Old communism viewed the rich as oppressing the poor. New communism has a similar view, but instead of focusing on disparities between individuals, it focuses on disparities between identities.
Feminism is a type of new communism. It portrays women as oppressed, and men as oppressors. Feminism does not demand that all individual men and women have equal outcomes, although many feminists profess old communist views in addition to feminism. Instead of equal outcomes (equity) between individuals, feminism demands equal outcomes for men and women as collectives.
At least, that is the ideological position. In practice, feminism is used to justify preferential treatment for women at the expense of men. It justifies this by focusing on certain disparities, such as income, while ignoring others, such as life expectancy. It also denies the biological basis of sex differences, claiming that they are caused by oppressive social constructs, not DNA. Feminism depends on a complex web of lies, but it is based on a simple moral premise: that men and women should have equal outcomes, not as individuals, but as collectives.
See What is Feminism?.
New communism shifts the focus from economic outcomes to emotional and cultural outcomes. Oppression is not just a matter of making more or less money. It is a matter of cat-calling, micro-aggressions, being marginalized, not having a voice, cultural appropriation, bullying, slut-shaming, body-shaming, and so on. New communism focuses on the subjective feelings of the oppressed, not their social conditions. Old communism demanded that society be transformed to create economic equality. New communism demands that culture be transformed to create experiential equality.
Instead of the redistribution of wealth between individuals, new communism demands the redistribution of status between identities. It demands the transfer of status from whites to other races, from Western culture to other cultures, from Christianity to other religions and to atheism, from men to women, from heterosexuals to homosexuals, from nuclear families to single mothers, and so on. White people, Western culture, Christianity, men, heterosexuality, and the family are all denigrated and pathologized, while everything else is celebrated and normalized. The point of this cultural engineering is to redistribute status.
New communism also doesn’t demand much of its adherents, except that they BELIEVE. It offers people low-cost morality. They don’t have to make any major sacrifices. In fact, they can be self-absorbed, narcissistic consumers, as long as they profess the right beliefs and feelings. Like most ideologies, new communism turns people away from fixing things in the real world. It tells them to use their time and energy to promote the ideology. It provides individuals with an excuse for personal failure and apathy, and an easy way to claim moral superiority. The new communists get to look down on their cultural adversaries as ignorant or evil: as bigoted, racist, xenophobic, misogynist, etc. It gives its adherents a claim to moral and intellectual superiority that is based solely on their beliefs, rather than their actions or practical achievements.
New communism promotes big government and big corporations, so it fits well with crony-capitalism. The new communists claim that Western societies are full of inequities and harm. Instead of viewing the government and corporations as the oppressors, they see oppression in the general fabric of culture and society, especially in the minds of white men. The government and big corporations are allies that can protect the oppressed and lift them out of their misery (using the wealth produced by those evil white men, of course). New communism promotes the capture of institutions, rather than their replacement.
New communism defines vague cultural and psychological forces (racism, sexism, homophobia, xenophobia, etc.) as the problem, and it sees the government and big corporations as the solution. The stupid, bigoted masses (especially those privileged white men) must be censored and indoctrinated. “Hatred” must not be tolerated. People must be educated to wipe out “ignorant bigotry”. New communism wants to use institutional power to install itself in every brain. The government and mega-corporations are only too happy to go along with the agenda of mass brainwashing, although their reasons for wanting it are somewhat different.
New communism gives wealthy elites a moral justification for power, and it doesn’t threaten their privilege. Instead, it collectivizes their “guilt” for being rich by assigning it to men or white men in general, and to Western culture and society. As long as elites profess the right beliefs, and make a few token gestures in the direction of “social justice”, they are considered to be good. They get to claim virtue because they have the right feelings and beliefs. New communism allows elites to keep their money and consolidate their power, and it even provides them with a moral justification for doing so.
New communism provides ordinary people with a cheap way to signal virtue, and it provides elites with a moral justification for power. That is why it has been so successful.
New communism grew out of the cultural milieu of the late 20th century West, especially in the United States. It emerged, as all ideologies do, because it was able to propagate itself from mind to mind effectively. It is not a conspiracy, although some conspirators might find it useful. It is a memetic plague.