Libertarianism is in fact what Conservatism used to be
Neither one of these assertions is true.
First, Ron Paul is a self-described Libertarian. He ran for president on the Libertarian ticket in 1988.
Second, there is nothing "conservative" about the Libertarian Party. Libertarians are only a philosophical step or two away from anarchists. They don't want small or smaller government, they want absolute minimalist government.
On most social issues, they are libertines, or nearly so. They want open borders, legalization of all drugs, an absolute minimalist military to go along with rock bottom minimalist government. In these matters, Libertarians and liberals are kissing cousins.