Democrats have been doing this for a long time
I suspect that newcomers to observing politics think that the Democrats have taken a sudden turn to the left. But the truth is, “progressives” have been at this for a long time.
Here is a little poem that dates back over 60 years that shows that this behavior is not new.
Democrat poem from 1949 (click to see full size)
The progressive movement started in the early 2oth Century. The goal was to cure many of the ills of American society that were created during the industrial expansion during the late 19th Century. Many social programs such as public education, the Interstate Commerce Act, environmental conservation, and food and drug laws were products of the early progressive movement.