Puritan society required that its members follow strict guidelines of social order. These rigid rules of conduct helped the Puritans endure the persecution they faced in Europe and, after they came to America, created a close-knit community able to withstand the harsh weather and Native American attacks common to New England in the 17th century. But communities that focus primarily on social order leave no room for personal freedom. Those who think or act independently are seen as a threat to the community: they must therefore be swiftly stopped or eliminated.
An excessively strict social order also provides no outlet for personal grievances. Over time, unvoiced resentments build up among individuals, primed to explode. The witch trials depicted in The Crucible can be considered an attack against individuality: those accused and convicted of witchcraft were mostly people who prioritized their private thoughts and integrity above the will of the community. The trials provided a legally sanctioned forum for the expression of anger and grievance. If your neighbor once sold you a pig that died soon after you bought it, and that neighbor stands accused of witchcraft, it seems only natural to bring up the dead pig as possible evidence. The trials also gave people like the Putnams the chance to voice their festering bitterness by accusing those whom they had quietly resented for years.