There are of course more possibilities in chess. The 8x8 kind of checkers popular in English speaking countries is a bit of a children's game. Proper checkers (10x10) is not to be sniffed at since indeed no human can see everything OTB. Engines have been said to play the best moves for years.
I started with checkers as a kid since nobody played chess, and then moved on later. Played some tournaments and was one of the strongest youth players in the area in both chess and checkers. After all you quite simply use the same principle of centralization and calculating forced variations. I don't see why a chess player can't be a decent checkers player and I consider myself about equal in both, if I deduct the years of chess practice of course.
That is a fascinating story. How quickly he was snatched by fate.