The biggest reason the left and the right of American politics fight on issues of social policy has to do with the diverging views of what the role of the federal government is.
To the right, the federal government is analogous to a neighborhood association (NA). In a NA, the residents get together and vote on common rules for everyone to follow as well as an association fee that each neighbor has to pay in to the general fund to pay for things such as trash pickup, snow removal, lawn car and common area maintenance.
One could not imagine anyone in a NA begin to suggest that the NA start also paying for individual health insurance or that how much we pay in should be based on how much we make. But there is nothing actually preventing that from happening. It's only that such an idea is preposterous and would result in the wealthiest residents moving.
The book Atlas Shrugged works on a similar premise. What if the people who make all the money simply went on strike? What if they simply stopped producing and went away? The book shows how society, as we know it, would soon collapse.
That's because, in the real world, in any random group of people, a tiny handful produce most of the results for the rest. This is true whether you're talking about a small project or even in a given neighborhood where most of the work is done by the same few people over and over again.
When the far-left clamors for the government (the ultimate neighborhood association) to provide more and more benefits to individuals, they are hijacking the original intent of the founding fathers. Someone who argues that a politician who votes against expanded benefits for individuals is somehow a "Scrooge" has a fundamental misunderstanding of what the purpose of government is.
Which brings us back to our neighborhood association. If your neighborhood association began to try to force the most productive members of the neighborhood to provide disproportionately more to the neighborhood than what they receive in return what do you think would be the result?