Prior to the 2020 election the Hatfield vs McCoy pejoratives seemed to be “extreme right wing” vs “liberal”. The latter has faded away. Now it’s “progressive”. Why? I think because it denotes a more definite leftist position. This type of labeling goes back a ways.
“The French Revolution set up the spectrum of political views in Europe for the rest of the 19th century. On the right were supporters of royalism and the traditional power of the church; on the left were anarchists and socialists. Liberal republicans, supporting popular sovereignty and individual liberties but with strong property rights and a growing capitalist economy, were in the middle.” -Prof Lawrence Cahoone