pawns determine piece activity and the amount of play. If one side is able to expand on one side of the board and shut down the other, then their game will be very simple to win. One example is shown below.¶

fen: r2q1rk1/p1nbppb1/3p2pp/1ppP3n/4PP1B/2P2N2/PPBQ2PP/R2N1RK1 w - - 4 15
id: _bG2ZRrD

clearly g5 is weak due to h6, but normally the U-boat structure that f5 would induce would create a huge hole for B's pieces. In this case though, there's no way for the knights to easily reach e5. so we can safely push f5