Liberalism, progressivism, and even further leftward ideologies like Marxism-Leninism can not deliver a society in true equality, solidarity, and liberty. The ultimate goal of a human society should be to allow the free exercise of self-directed, self-improving activities for all people. The main obstacle to this within the systems mentioned above is hierarchy. Examples of hierarchies extant within these systems are: statism, capitalism, racism, ableism, and cisheteropatriarchy. On their own, these systems may be able to address a few of these, but they are all still reliant on the hierarchy of the state.
Marxism-Leninism, for example, still requires a state hierarchy to oversee the will of one class (workers) over another (bourgeoisie). While there can be no question that in order to achieve a truly egalitarian society the bourgeoise must be stripped of their class consciousness, in the long term this only serves to create a distinct political class that ultimately will work to advance their own interests over that of the workers they claim to represent. We can see this in the failure of every M-L or vanguard socialist state (USSR, China, Vietnam, etc) to ultimately transition into the stateless society that Marx envisioned. It is easy enough to blame the CIA and capitalist efforts for these failures, but Occam's Razor will pretty clearly illustrate that it is in fact the self serving interest of the political class that leads to this failure. Similarly, liberalism and progressivism require the presence of "legitimate" violence and coercive authority to function.
Therefore the only system which has a hope of establishing true egalitarianism for all humans is anarchism. A horizontal, directly democratic system built on the foundations of solidarity, equality, and liberty. It is the onus of hierarchies to establish their legitimacy through their benefits to human society rather than through monopolized violence as is currently the case. Control of the means of productions by workers councils, automation where jobs are genuinely undesired, ability to explore other human pursuits not valued by the market system. The destruction of racism, ableism, and cisheteropatriarchy through solidarity and the abolition of social hierarchies. No gods, no masters.
For more, please see:
Or fee free to ask me questions here. (Note: I am not the creator of the video.)