Over the years, many great pedigrees have been forgotten or stripped from coins as they reappear for sale. If you were a collector, wouldn't you like to know that your anonymous new purchase was once part of the Eliasberg, Norweb, or other great collection? Here's an example:
This 1810 Half Cent was sold in the Goldbergs 6/2005 sale (Lot 14) without a pedigree. It reappeared as Lot 135 in their 2/2018 sale, there pedigreed to the Green Tree Collection. The coin plate-matches perfectly to the Eliasberg Collection, thus yielding the following pedigree:
M.A. Brown Collection - S.H. & H. Chapman 4/1897:1005, $3 - John M. Clapp Collection - John H. Clapp Collection, sold intact in 1942 - Louis E. Eliasberg, Sr. Collection - Bowers & Merena 5/1996:434, $3,080 - Goldbergs 6/2005:14, $4,485 - Green Tree Collection - Goldbergs 2/2018:135, $4,465
I'm betting that the new owner of this coin would be thrilled to learn of the expanded pedigree. Wouldn't you?