A group can misunderstand what its members privately think
People sometimes privately reject a group practice while assuming that most others support it. If everyone stays quiet because of that assumption, the practice can continue. Pluralistic ignorance describes this mismatch between private views and beliefs about the views of other group members.
Go deeper
Silence can create a misleading social picture
Suppose several members find a recurring meeting unhelpful. Each thinks the others value it, so nobody raises the concern. Their silence then appears to confirm that the meeting is popular.
This is pluralistic ignorance: people misperceive the attitudes of others, often while their own private attitude differs from the public norm.
It is more specific than simply disagreeing with a group. The key is that multiple people misunderstand what others actually believe.
The pattern can sustain an arrangement even without strong support for it. An open discussion or an accurate anonymous survey may reveal that the apparent consensus was based on mutual misreading, though silence alone cannot establish that such a mismatch exists.