A lot of this is a recent phenomenon, IMO, due to educational polarization. Attachment to liberal values is heavily tied to class and educational attainment, and high-mid/low-high income + high education used to be split to flat out GOP lean until the early 2010s.
I think the issue is that people confuse social conservatism with political conservatism. They overlap but are not really necessary To me the core of any liberal con isn't their views on gays or abortion but an intrinsic skepticism or outright fear of the masses
Its what truly separates any such person from leftists, who believe in the intrinsic positive value of an engaged active population. A lib con would lean on the danger of excited the population to much, on a fear of the mob and demagogues. I mean its plainly there in John Stuart Mill