Plato didn't have much written history to make more than an Idealist stab at what needed doing in his REPUBLIC. At least, he made the political equality between men and women part of his proposed utopia. We've seen social relations change a lot since the 5th Century BC. Back then, slavery was considered an unchanging norm of society and to be sure, Greece at that time was a class dominated society, even though Athens had a political democracy, limited as all political democracies are, to empowering the those with ownership of property over those without ownership of property. Remember, slaves and women were considered property in that era.
Social relations of power are grounded in material relaties of wealth ownership. I would argue that those relations have changed and have been changed by an rising sense of entitlement to freedom and democracy. The historical process has been slow; but it is inexorable because it is firmly founded on a part of our human nature to wit the instinctive desire amongst all animals not to be caged, tied down or fettered and instead to be free.
To be sure, to be free in nature is to be more or less totally dominated by nature. A lion cannot live outside its hunting ground unless it is caged and fed at a zoo. Survival is a strong driving instinct too.
When humans are able to dream and plan for a better, freer world, they start forming that new world within the womb of the old world. Looking back at history, we can see this developing consciousness emerging in the ancient, feudal agrarian societies which dominated before the 15th Century AD...and then came the invention of the printing press, literacy for the many in the venacular as opposed to just for the few in sacred languages/foreign tongues of the past and so on......under all, lay the drive to become freer, an instinctive drive.