This exchange slightly relieves the cramp in Black's position.

The White K will now march unopposed towards the centre to support his Q-side pawn majority.

Black has managed to get his Rs onto useful files and can now think about a K-side pawn rush.

This looks to me like a diversion. With the White K now optimally centered, I expected a pawn steamroller: b4, c5, etc.

This looks menacing, but, as the sequel shows, White would have done well to have kept a R on the first rank.

This allows Black to trade off the backward e7-pawn, which somewhat relieves the cramp in Black's position. I expected b4 or c5 instead.

Black has converted his pawn majority into a dangerous passer which White cannot ignore. Barring any blunders, this should equalize.

This leads to a safe draw. Whereas, 42. Kc5 b6+; 43. Kb5 h2; 44. Ka6 Rb1 leads into muddy waters.

Forced; if the White K stays on the third rank, then Black queens the h-pawn after a back-rank check.

Black can now safely shuttle between c7 and d7 indefinitely.