Groupthink is a very well-documented psychological tendency of humans to tend to agree with each other, and hold back objections or dissent even when it is obvious to them that the group is moving strongly in a very wrong direction.
Groupthink is sometimes misleadingly referred as community values: there are no "community values". Communities are compromises of values created to achieve bodily protections. The community shares no values other than protecting its own bodies.
One way to control groupthink is to steer it into factions that can at least have sharp differences with each other. In democracy this means dividing into political party structures that debate the actual policy while a bureaucracy implements the policy only of the ruling party.