It is true that reformers found many faults with the practices of the Catholic Church.
Protestant's.
Protesetants
Reformers set up a system of free public elementary schools. The Catholic Church was in charge of education previously.
To go against the catholic church.
There were no reformers. The Catholic church was in full control of the society.
The overall corruption of the church was a big concern. The biggest example of the church's corruption was the selling of "indulgences" by the Pope and the Catholic Church.
To go against the catholic church.
.Catholic AnswerThere were no reformers outside the Catholic Church, there were only protesters who left the Church and formed their own ecclesial communities. The Catholic Church was established by Our Blessed Lord, Jesus Christ, who sent the Holy Spirit to guide it always. Our Blessed Lord guaranteed that the Church, which is HIS Mystical Body, and His Bride, would remain spotless till the end of the world. You are asking about the protestant revolutionaries like Martin Luther, and Henry VIII. They were in no sense "reformers", that is a gross misnomer.
.Roman Catholic AnswerMost of the people who protested against the Church in the sixteenth century were heretics and apostates. Today they are, more politically correct, known as "protestant reformers" by those who followed them.
.Catholic AnswerBasically a grudge against a Church which held to the moral teachings of Our Blessed Lord, Jesus Christ, and told them both that they had to be moral, and that the faith could not change.
The Catholic Church did not view them as reformers so much as revolutionaries since they sought to enact their desires without the sanction of Church authorities and ended up not reforming but rejecting those things they found problems with. The Church considers such actions heretical and thus saw them as heretics. Those that were personal responsible for these breaks are considered heresiarchs, or leaders of heresy. There were some clerics and people who strove for reform but decided to do so while staying with the Church, believing Her inviolable. Some of these reformers became saints.