How do you determine what is a bad idea, and how does it get rooted out?
Look at how long it has taken the Catholic Church to change in important ways. They still struggle with big issues. The LDS Church will change slowly. Ending polygamy. Extending the priesthood to black men. Positive changes, but they took a long time.
It took sustained anti-Mormonism to bring about those changes.
The Community of Christ has moved more quickly but at a great cost. Those are two sects grounded in the Restoration.
What was the great cost?
Premise 1. Eyewitness testimony is notoriously unreliable.
Premise 2. The best evidence for the Book of Mormon is eyewitness testimony.
Conclusion. Therefore, the best evidence for the Book of Mormon is notoriously unreliable.