Why did Martin Luther's posting of the Ninety Five Theses spark the Protestant Reformation when there had already been calls for church reform in the past?

Martin Luther's posting of the Ninety-Five Theses in 1517 sparked the Protestant Reformation primarily because it effectively utilized the new printing press to disseminate his ideas widely and quickly, reaching a broad audience. Unlike earlier reformers, Luther's arguments against the sale of indulgences and church corruption resonated with widespread discontent among the populace and clergy alike. Additionally, his emphasis on faith and scripture over church authority encouraged individuals to question the Catholic Church's practices, leading to a significant shift in religious thought and practice. This combination of timely communication and compelling theological arguments mobilized a movement that challenged the established church more vigorously than previous reform efforts.