Yet there is more to the focus on class than just the moral argument. The reason socialists believe that class organizing has to be at the center of a viable political strategy also has to do with two other practical factors: a diagnosis of what the sources of injustice are in modern society, and a prognosis of what are the best levers for change in a more progressive direction.
Workers are therefore not only a social group that is systematically oppressed and exploited in modern society, they are also the group that is best positioned to enact real change and extract concessions from the major center of power—the bankers and industrialists who run the system. They are the group that comes into contact with capitalists every day and are tied in a perennial conflict with them as a part of their very existence. They are the only group that has to take on capital if they want to improve their lives. There is no more logical force to organize a political movement around.
[...] One consequence of rapid industrialization was bringing huge numbers of former peasants together into new factories where they rapidly got absorbed into trade unions and were quickly radicalized. But now since workers don’t stick around in the factory long enough to be politicized, to be drawn into organizations, it means that economic development and urbanization isn’t bringing with it a kind of radicalized working class the way you saw in the past.
that is actually quite a good insight and not really one I'd thought about before
I think the first step towards that is to see that the fundamental problem these days is not North versus South, the fundamental problem is that in any country where working people try to raise their voice, the first power they come up against and they have to confront is their own ruling classes.