When the Gospels describe disciples eating with "unwashed" hands, modern readers can easily imagine a dispute about cleanliness or germs. The controversy instead concerns ritual practice and the authority of traditions governing purity.
The issue becomes a test case for a larger question: what truly defiles a person before God?
Jewish purity practices grew from biblical concerns about holiness and ritual cleanness, while additional traditions developed about how purity should be maintained in daily life. Handwashing before eating could therefore have religious significance beyond removing dirt.
The Gospel controversy specifically associates the practice with "the tradition of the elders." It should not be reduced to modern sanitation, nor should every later rabbinic detail automatically be assumed to have operated identically in the first century.
Recognizing the ritual setting makes Jesus' response much clearer. He is not encouraging people to eat with filthy hands. He is challenging the assumption that ritual contamination of the hands identifies the deepest source of human defilement.
The discussion moves deliberately from external practice to the moral condition of the heart. That movement is easy to miss when the passage is read as an argument about personal hygiene.