Answer:
Step-by-step explanation:
Religions have reformers because they are "alive" like everything else, they change with the passage of time. If we're talking about Christianity here, there was a protestant reformation because Martin Luther realized that the church's traditions had lost sight of God. He saw them encouraging and profiting from indulgences which by scripture was sinful. He believed (and was backed by scripture) that faith was attained through faith and good works not by paying off the church. In conclusion, reformations occur because people ask questions.
Opinions can change depending on the religion and the targeted people. But, for the most part, reformations occur mainly because people are good at asking questions and knowing when something doesn't "add up".
Good luck