In many games greater familiarity with the biases of the dice would be no more an advantage (sometimes considerably less) than greater familiarity with the game rules and strategy. It's not clear what games were played, or whether they were played repeatedly amongst groups or by strangers competing against a "house". The article does suggest the biases were visible enough for such games to not hinge upon a particular participant's false believe in the uniformity of the dice though, as well as hint most people's betting strategy probably wasn't sophisticated enough for them to care