It is a question of move order.
1...Ne8 2 Qd2 cxd5 3 Nxd5 is good for white with the central knight outpost and the tempo won on the black queen.
Also 1...Ne8 2 Qd2 Nd6 3 O-O-O is good for white, who gets an attack.
1...cxd5 2 Nxd5 Nxd5 3 cxd5 is good for black with his queen's side pawn majority.
Hence first 1...cxd5 2 cxd5 Ne8 intending blockade 3...Nd6 with a queen's side pawn majority.
Hi,
below is the position from my recent game as black in which I played Ne8. Chess.com engine marks it as an error and suggests the best move cxd5 of which I did not think during the game. My question is what good does cxd5 bring? I can see that it frees the right diagonal for my bishop on d2, but is there anything else?