Why does historian Doris Bergen say it is important to not "rush to the gas chambers"?

the second significant cause of the great migration was the desire of black southerners to escape segregation, known euphemistically as jim crow. rural african american southerners believed that segregation - and racism and prejudice against blacks - was significantly less intense in the north.

to reform the distraught soviet union, the democratization of the communist party was promoted through party secretary mikhail gorbachev's policies of “perestroika” and “glasnost.” perestroika refers to the reconstruction of the political and economic system established by the communist party.

what are the options?