The class against class ideology was a bit more complicated, finessed dependent upon the needs of the time. It was the raison-d'etre behind the Land reform campaign in the mid 1950s, and remained the guiding light for admitting and promoting cadres within the party hierarchy. Tho to Vo Nguyen Giap. However, it's interesting to note that this does not mark the end of dissent, only the end of open dissent. Edward Said's critique of this state of affairs is well known.
Excessive oppression leads to excessive anti-oppression.
The SVNese government never had control of the war, and the SVNese people never had control of their government. Historians can include and study lots of competing voices. For the VN war, American historians, however, have done an outstanding job in this regard.