because members believed in a strong federal government
Federalists believed in a strong central government with representatives to be the voice of people. They supported a small group of representatives and wanted them to be elite members of society. The Federalists supported the Constitution as written and didn't see the need for a Bill of Rights.
The counter to the Federalists were the Anti-Federalists led by Thomas Jefferson who believed the power should rest in the hands of the state and the people. They were more likely to support direct democracy and more people involved in the government.