Because all the southern DINOs were carved off by Reagan. Remember the "boll weevil caucus"?

Nope. It's much more recent than that. If you click through to the link, as recently as 2007 more Democrats self-identified as "moderates" than "liberals" - and it wasn't until 2016 that a majority of Democrats self-identified as liberal. In 1994, when Bill Clinton was President, about 48% of Democrats self-identified as moderate and 25% self-identified as conservative. Even as recently as 2009, 60% of Democrats self-identified as moderate/conservative. But since the Obama election - the "Great Awokening" - that's changed.

For as long as Gallup's been doing that poll, the GOP has been heavily majority conservative and <10% liberal. The Democrats used to be much more mixed, and was the home of more moderates and a fair number of conservatives, but that's shifted heavily in the last 16 years.

Here's the link again:

news.gallup.com - Democrats identification liberal new high