You would benefit from reading the introduction that Miller gives us to the time period that is positioned at the very beginning of Act I, before we see Parris worrying about the mysterious sickness that his daughter Betty has. In this lengthy description of the time and period, Miller gives a great analysis of the factors that contributed to the with hunt becoming such a "success," and in particular the way that individuals were able to contribute to the scenario by being able to personally profit from the situation:
Long-held hatreds of neighbours could now be openly expressed, and vengeance taken, despite the Bible's charitable injunctions. Land-lust which had been expressed before by constant bickering over bounderies an deeds, could now be elevated ot the arena of morality; one could cry witch against one's neigbour and feel perfectly justified in the bargain. Old scores could be settled on a plane of heavenly combat between Lucifer and the Lord; suspicions and the envy of the miserable toward the happy could and did burst out in the general revenge.
Thus a big factor that Miller cites as contributing towards the witch trials is the way in which unscrupulous individuals, which are of course symbolised by the Putnams in the play, coldly used this opportunity to denounce their neighbours for personal benefit.
I would think that the opening scene, and the stage instructions that accompany it, would give much in way of detail as to why Miller believes that Salem, itself, is to blame for its own witch hunt. The attitudes of Paris about children are similar:
... [Salem and Paris] never conceived that the children were anything but thankful for being permitted to walk straight, eyes slightly lowered, arms at the sides, and mouths shut until bidden to speak.
Such strong repression of youth is a factor in the girls' action. Miller makes the argument in the opening section that the girls' desire to dance and be youthful would be seen as sinful by the parents and the community members. In avoidance of this, the girls lie and this becomes the basis for the witchhunt. The need for repression of youth is reflective of Paris, himself described by Miller in this first act as possessing "a driving need to be in control." This helps to explain the witch hunt as an event that sought to consolidate control of those in the position of power. The last point that helps to explain why Miller feels that Salem, itself, is to blame for the witch hunt would arise from the “predilection for minding other people’s business.” This intrusive element of Salem society made it easy for people to become suspicious of people for the smallest of things and also made it easier for individuals to eviscerate realms of privacy in order to make everything public. In this light, Salem becomes victim to its own hypocrisy and its own poor decision making, making it ripe for something like the witch hunt to happen. However, Miller does not miss the opportunity to make it clear that these realities are applicable to all social orders, and their presence has to be understood. While there were conditions in Salem that allowed the witch hunt to take hold quickly, Miller forces the reader to assess the same situation in the modern setting, as well.