The short answer is that someone had a bright idea, created charts for researchers to fill out on paper, sold the charts to researchers and publishers, etc. The creators probably received no profit from their invention and are virtually unknown to current researchers.
Here are some interesting patents found in Google Patent Search (with links to the US Patent and Trademark Office):
* 0,324,535 "Game Apparatus" by Samuel L. Clemens, issued 1885
* 0,432,148 "Genealogical Chart" by Oscar W. Rogers, issued July 1890.
* 0,458,358 "Chronological Chart" by John A. Cole, issued August 1891.
* 0,527,261 "Ancestral Record Book" by Frederic J. Bailey, issued October 1894* 0,627,718 "Genealogical Chart" by Robert H. Chapman, issued June 1899.
* 0,699,799 "Chart for Recording Ancestry" by Georgiana Guild, issued May 1902.
* 0,705,833 "Genealogical Chain Record" by Pattie Williams Gee, issued July 1902.
* 1,058,859 "Chart" by Norman C. Gray, issued April 1913
* 1,098,833 "Genealogical Record" by J. B. Olinger, issued June 1914.
* 1,297,663 "Genealogical Chart" by Herman S. Davis, issued March 1919
* 1,447,279 "Means Employed in the Art of Keeping Family Records" by William W. Carson, issued March 1923.There are quite a few more - and later in the 20th century people started inventing genealogical games!