Exactly. White forced a fair trade when ahead in material ♗ versus ♙♙, simplifying to a winning endgame. And with the queens and rooks now off the board, Black has no chance to launch a desperation counterattack. Black can only grovel in a losing endgame.

Yes, that part about freeing the knight is very important. I quickly saw the knight fork but then I worried that my knight would be trapped and eventually lost to Black's king (... ♔x♘).

Many of the solvers apparently didn't even consider this possibilty, stopping their analysis after 35 ♘x♕. <Never stop analyzing when you have a piece trapped on the enemy's side of the board!> If this knight had indeed been trapped and lost, White would be down two healthy pawns for nothing, almost a certain loss.

Asrian clearly had the <knight-rescuing idea> 36 c4, 37 c5, and 38 c6 in mind before he began the combination.

That is, since the Black c7-pawn is the only Black unit stopping White from playing c6-c7-c8=♕ by <blockading> the advanced White c6-pawn, it cannot also <defend> the b6-pawn. Black's c7-pawn is simply <overworked>, having to both <blockade> the White c6-pawn and <defend> the Black b6-pawn.

So can someone explain how this qualifies as a "nice" or "interesting" puzzle? From what I can see, it is a straight swop of R+Q for R+Q producing a marginally better end game for White. Is that it?

I suppose there are two things that I didn't notice which means that I did not get the puzzle.

1. There is probably no better line for white than the played line.

2. The played line resulted in white's Knight coming perilously close to being trapped which required some deeper planning than just to the fork on King and Queen.

I immediately saw White is a piece up and black's superior pawn structure as the imbalance in the position. I felt any solution had to incorporate correcting that imbalance, even to the point of returning a piece to accomplish it. So after RxR,NxQ,KxN,QxP I thought this sucks, other lines seemed worse so I just looked at the game.

I think,though, White can win by omitting f3 and bringing the knight out via c6: 35...Nd2 36 Nb8 a5 37 Nc6 f3+ 38 Bxf3 Nxf3 39 Kxf3 bxc6 40 b4. Or 35...Nd2 36 Nb8 f3+ 37 Bxf3 Nxf3 38 Kxf3 a5 39 Nc6 bxc6 40 b4. Or 35...Nd2 36 Nb8 a5 37 Nc6 bxc6 38 b4 Nb3 39 Bc4 Nd2 40 Ba2 when the knight is cut off. In all cases, Black probably cannot stop the a pawn.