6-5 blackjack significantly increases the house edge compared to the more traditional 3-2 payout for blackjack. In a 6-5 game, players receive a lower payout on natural blackjacks, which decreases their overall return on winning hands. This results in a higher expected loss over time for players, making it less favorable than standard blackjack. The combination of diminished payouts and the same basic house rules leads to a less advantageous situation for players, emphasizing the importance of payout structures in determining the game's profitability for casinos and fairness for players.