Socialism, a system of government that allows complete government control of some or all sectors of a nations economy, does go against American based ideals. The problem with socialism is that it allows the government to monopolize an industry. A monopoly is still a monopoly whether or not it's held by a company or a government, and with a monopoly comes all the negative effects normally associated with monopolies.
Monopolies hurt consumers, they reduce innovation, cause prices to rise, and limit production.
Canadian health care is an example of socialism in action. Everyone is covered by the country's health care system. The effects are higher taxes, and long waiting list for much needed medical procedures that cause people to cross the border to the United States, and pay for their treatment expense out of pocket. Not only does socialism hurt the economy, it also gives rise to totalitarianism and other negative forms of Marxism, like Communism. In the former Soviet Union, China and Cuba most of the middle class has been totally eliminated.