The article doesn't even say what game he was playing. It wasn't necessarily blackjack, which as you observe doesn't confer a big advantage by knowing the enemy cards since your bet is already set and your strategy mostly is. Poker permits the most leverage for knowing hidden information, but in poker you scam the other players, not the casino (casinos very rarely offer poker games played against the house.)
Maybe it was Pai Gow Poker, which does have strategy that can be exploited by knowing the dealer hand you need to beat, and is often played for high stakes in VIP rooms.
Maybe it was Pai Gow Poker, which does have strategy that can be exploited by knowing the dealer hand you need to beat, and is often played for high stakes in VIP rooms.