This phrase is the basis for enforcing an equal society

This is the basis for having an equitable society. If someone needs insulin to stay alive, they have a greater need and receive greater resources so the quality of their life doesn’t diminish. Some people have needs so great that with an equal share of resources they would just die as their equal share would be insufficient to their needs. Should dialysis patients just die or also have their needs seen to while maintaining a reasonable quality of life?

There is no situation where a caste system results in a more equal society

This is a weird tangent you went off on that’s unrelated to my comment