Cryptographic hashing can be used to prove your RNG/shuffling algorithms are provably fair. This is fine for player vs house games like dice and blackjack but it doesn't do anything about superusers in poker where the house leaked hole cards of other players to them. There is a technique called "mental poker" where every player's client module participates in the deck shuffle with encryption such that the house doesn't know the cards. But it falls apart if any player disconnects (accidentally or on purpose) and doesn't protect against a corrupted client that leaks your decrypted hole cards.