That's because anyone who studies history knows that the Catholic Church is the only one that goes back that far.
As someone once said, "To be deep in history is to cease being a Protestant"
The followers of Joseph Smith will tell you that he ws a legitimate leader even though he didn't come on the scene until the 1800s
Other folks tell you it was some other person / group
But none of them can be traced back to Christ and the 12
The Coptic church goes back to 42 AD.