I have observed a constant factor among what are roughly considered 'leftist' ideologies which appears to transcend what broader philosophy the leftist may advocate. This factor is the desire to create a system by which non-producers (those who consume more than they produce) can survive in relative comfort.
This goal can be seen in the communist mantra of "from each according to his ability..."; the Georgist concept that productive land users should pay "rent" to the non-producers; the growing push (even among some 'libertarians') for a "universal basic income" (UBI); the push by "post-scarcity" utopians for a central (sometimes AI-based) system to "equitably" allocate goods and resources; and the existing system of progressive taxation and redistribution.
Contrast these notions with the 'Conservative' or right-leaning philosophies which take the opposite approach. Consider the quote by the colonial leader John Smith in Jamestown, Virginia who said, "He who does not work, neither shall he eat." This concept has been generally embraced by traditional conservatives, Objectivists (Randians), libertarians, Voluntaryists, and anarcho-capitalists.
Under the systems (or lack thereof) envisioned by these latter philosophies, individuals who don't produce would be forced to rely on voluntary charity provided by those who do produce. This is the only concept fully compatible with voluntary action, as the ideas embraced by leftists all involve someone (or something) using force to take property from producers and redistribute it to non-producers.
Fundamentally, leftism is based on using coercion and force to steal property. When you understand that All Rights are Property Right, it becomes clear that leftism is necessarily anti-rights because it is overtly anti-property rights. It crafts a facade of benevolence to mask its assault, but the underlying coercion is undeniable.
Concern for the truly less fortunate (which is but a small subset of non-producers) may be laudable in a general sense, but using force to steal property is never justified, no matter how benevolent one's intentions may appear.