The radicals who now dominate the Democrat Party long ago realized that they could never win by making plain their plans to overthrow the established Constitutional order. "Revolution Now!" does not poll well.
Accordingly, and with the assistance of professional leftist organizations funded by globalist billionaires like Tom Steyer and George Soros, the Left's newly-elected radicals have learned how to control and manipulate the language. The development of phrases such as "Economic Justice", "Green New Deal" and "Medicare for All" is not an accident; it is the product of strategy and research. He who controls the language controls the debate, and Democrats know from long experience that Republicans are terrible at playing that game.
And so, the Left now pretends to be moderate and reasonable while planning for extreme change, even if it must be accomplished incrementally. AOC and the rest of the Odd Squad may too often let the mask slip, but make no mistake: they are not Democrat back-benchers, but the Vanguard of the Revolution. Otherwise, they'd be told by Democrats to shut up and sit down.