The word "always" implied that the states should obey the federal government under any circumstances.
Most of the times, yes. I think it is important for the states to obey the federal government in order to maintain law and order in the country.
But, there's a chance that the federal government might impose a legislations that's violates the constitutions or human rights. At that point, the states need to be able to raise as the opposition from the central government.
