Democrats have become steadily more socialist/progressive over the last 5 decades
It has worked because they have the entire apparatus of government, our printed/fiat currency, and massive debt behind them
Don’t doubt they will continue to push leftwards, as long as conservatives allow our present monetary and government system to continue.
Long gone are the days of Truman, Humphrey, and JFK -— democrats that were respected by all -— even the pubbies.