If there has been such a trend, I attribute it to this: A lot of social conservatives left FR after the Buchanan Brigade debacle, while most of the socially liberal libertarians stayed around. That skewed the social conservative / social liberal ratio on a lot of threads.
Additionally, a lot of social conservatives on FR still tie their conservatism to causes like opposition to Bush and the Republican Party. That's obviously going to annoy most Freepers, who are largely Republicans and Bush supporters.