The reason is that they do not recognize any sector that has a right to be private, if a majority of the legislature decide to stick their fingers in and start running things. Likewise, with that mindset, "limited government" under a written Constitution has no meaning to the socialists.
Today's socialists, liberals, progressives, left-Democrats, whatever, parted company from us in 1776. They neither know nor understand the genius of the success of America since then. They also neither know nor understand the nature of free market economics, which began the same year with the publication of Wealth of Nations, by Adam Smith.
Congressman Billybob
Quite. I like to think of market economics as a system which maximizes effective communication - much like the Internet. It's been said that nobody knows how to make a pencil - the people who know how to produce the graphite don't know how to grow timber or reduce it to lumber or how to mine the metal for the eraser ferrule or how to make the rubber for the eraser. But market economics draws that information together in an effective and efficient way. Socialism is the arrogant conceit that a planner can do better than the market, and because of inherent chaos in the system - weather conditions, changes in technology . . . the problem which the "smart" central planner tries to solve mutates faster than the planner can react - never mind plan.Which is just another way of saying that the "smart" central planner may know a lot and still might instantly lose his shirt if he durst bet his own money in a real market. In the market system diffuse intelligence changes prices, and those prices change people's plans - which then change prices anew. Socialists simply assume their own superiority over the diffuse intelligence of the market - and demand that you prove them wrong. But the conservative knows that if he could explain that he would be a competent central planner - and he knows that he is no such thing.