I'd think that the other player's Pawns could whittle that down pretty effectively
I am not so sure, if the defender tries to avoid trading Pawns as much as possible, but instead pushes these forward when they get under attack. It only requires two interlocked Pawn chains of opposit color to make an impenetrable barrier.
Both players also have lots of Knights that can jump over and break that barrier.
Both players also have lots of Knights that can jump over and break that barrier.