It is true that ultimately, responsibility for shepherding of believers rests on God Himself. Its why Jesus demonstrated that with the 12 disciples. We are not all endowed with the same capacity for understanding of spiritual truths, however, which is why God places teachers, pastors etc. in church.
There are believers who need guidance of Christians who have a better understanding of what it means to be a Christian. The beauty of Christianity lies in the fact that the person placed in the church as teacher or pastor does not see himself or herself as superior to those who depend on his or her leadership. He or she does not fleece the believers because they depend on him or her for leadership or guidance. This is exactly where a lot of mega churches are misrepresenting Jesus Christ.
Ellen G. White received inspiration from God. If you read her writings, you will see Jesus in her writings. She is one of the most prolific women writers the United States has ever seen. I know people nowadays are wary of visions but there is nothing wrong with visions when the life and teachings conform with person of Jesus Christ. The litmus test always is the life and the teachings and on that basis she more than passes with flying colors. Her book, Steps to Christ is considered one of the classics of Christian writing.