“Moderate” is the new “progressive”. Notice that in every bastion of leftism, “conservatives” outnumber “liberals”, and “moderates” outnumber both.
Except the last 3 (MA, RI, DC).
Liberals or progressives are like a private club. A lot of people don't feel like they belong.
You can find people who hate all Republicans (there are a lot of people like that on the Internet), but they don't agree with the faculty or the city council of Cambridge or Madison or Berkeley, so they call themselves moderates. There are die-hard Democrats who blame the "liberals" for their party's defeats, so they call themselves moderates.
But the main thing is that the old Reagan Democrats in the red states became Republicans and even conservatives (or their children did). That didn't happen in the blue states. Some Reagan Democrats in the Northeast or Great Lakes or Pacific states did go over to the Republicans, but certainly not as many as in other parts of the country.
Many or most moderate Democrats (who were never as conservative as red state Democrats) stayed in the Democratic party and describe themselves as moderates. A lot of them aren't really very political or engaged. They just vote Democrat every election and then complain about what the government does. They complain about what the Democrats they elect do. And they complain more about the faraway Republicans they have only a sketchy conception of.
Maybe a Reagan running against a Carter or Mondale could dislodge them from their loyalties. A few became "security moms" or whatever you call Democrats who voted for Bush in 2004. But most of the time many of the children of Reagan Democrats in Democrat states vote Democrat.
I'd caution against assuming that they're all liberals or progressives under the skin. They just dislike Republicans more than they dislike liberals right now.