I’ve explained why 2. d5 loses in very detailed terms and with games to demonstrate, …
"... [Na3!] needs to be played and it needs to be played earlier than move 9. Otherwise white’s development isn’t rapid enough and black can catch up and draw. If white plays [Na3] earlier his position would’ve been crushing, but since he waited he only comes out with a small advantage" - staples13 (~1 day ago)
"... Black is better after [9...cxd4 10 Nb5 Qf5] in the above game, and it seems to me that white has to play 11.Bg3, as after 11.Nc7+ Kf8 12.Bg3 I do see a stupidly placed piece: The knight at c7, while the rook at h8 is doing just great after a quick ...h5. Oh, and white is a pawn down, with no obvious way to create some play. '[Na3] Needs to be played earlier than move 9' -when? …" - IM pfren (~1 day ago)
Are we going to see staples13 identify a specific pre-move-9 "crushing" improvement for White?
I’ve explained why 2. d5 loses in very detailed terms and with games to demonstrate, but I would like to state the reason here in the most simple and eloquent way possible
2. d5 immediately opens the center and since black lags behind in kingside development he can not survive white’s attack. 1-0