This is true, and whether you believe in Mormon doctrine or not, they provide a valuable service to those who are doing family research. My father in law, whose last name was Smith, was researching an ancestor about three generation back, and went to the local LDS ancestry library and asked for help researching his ancestor "John Smith." The way he tells it, it took a little time before anyone took his request seriously...

(Yes, the LDS archives did help him some, but the real treasure trove was in the files of a previously unknown cousin living back east.)