Are you not referring to a 19th century political philosophy that was adopted by mainstream modern conservatives (including Barry Goldwater)?
Yes.
Are not today's social conservatives some mutant (neo-conservative???) niche that has strayed from "true conservatism"?
I do not consider the modern "social conservatives" to be conservatives at all.
They are the ones that want government to keep out of the peoples personal business, except where they want government to intrude into peoples personal business [added--to enforce their particular religious beliefs].
Exactly.
The ones who might think of Barry Goldwater as being a liberal?
Barry Goldwater was a "classical liberal" (see Wiki description below). Today's social conservatives probably see him as being a (modern) liberal. Just another thing they are wrong about.
Are you one of them?
A social conservative? Not hardly. Wash your mouth out with soap!
wiki writes:
Classical liberalism is a philosophy committed to the ideal of limited government, liberty of individuals including freedom of religion, speech, press, assembly, and free markets.
Classical liberalism developed in the 19th century in Western Europe, and the Americas. Although classical liberalism built on ideas that had already developed by the end of the 18th century, it advocated a specific kind of society, government and public policy required as a result of the Industrial Revolution and urbanization.[2] Notable individuals who have contributed to classical liberalism include Jean-Baptiste Say, Thomas Malthus and David Ricardo.[3] It drew on the economics of Adam Smith, a psychological understanding of individual liberty, natural law and utilitarianism, and a belief in progress. Classical liberals established political parties that were called "liberal", although in the United States classical liberalism came to dominate both existing major political parties.[1] There was a revival of interest in classical liberalism in the 20th century led by Friedrich Hayek and Milton Friedman.[4]
In the late 19th century, classical liberalism developed into neo-classical liberalism, which argued for government to be as small as possible in order to allow the exercise of individual freedom. In its most extreme form, it advocated Social Darwinism. Libertarianism is a modern form of neo-classical liberalism.[5]
The term classical liberalism was applied in retrospect to distinguish earlier 19th-century liberalism from the newer social liberalism.[6] The phrase classical liberalism is also sometimes used to refer to all forms of liberalism before the 20th century, and some conservatives and libertarians use the term classical liberalism to describe their belief in the primacy of economic freedom and minimal government. It is not always clear which meaning is intended.