Playing Blackjack with fewer decks generally benefits the player by increasing the effectiveness of card counting, allowing them to better predict the remaining cards. With fewer decks, there's a higher likelihood of drawing favorable cards, such as 10-value cards, which can result in stronger hands. Additionally, the dealer is more likely to bust due to the card distribution, and the overall house edge is lower compared to games with more decks. These factors make the game more advantageous for players who can strategically adjust their bets and decisions based on the changing deck composition.