Our resource-base is limited. Resources should be husbanded, not squandered. Plus, the free-market doesn't exist anywhere in the world. If one is created, it is quickly swallowed by the mildly successful becoming big enough to monopolise. Of course, we would have to fix the government so it really does represent the people.
Social democracy can work if the proper measures are put in place.
Call them taxes, regulations, tariffs or subsidies, whatever, they will be necessary for a healthy society. The market is social democracy. In theory, government is the people. In practical theory, government is made up of representatives of the people. In practice, the representation is skewed and ineffective.