Why does everyone say that after d4 nf6 c4 d5 cxd5 is good

When obviously according to the database the strongest players play knight f3 or knight c3, or did I confuse the position? Because I think I also have read it in a book somewhere.

In that position, black can't take back with the pawn.
So you have to move the knight a second time or come out with the queen early. In both cases white gets a nice pawn center and slight advantage in development.
It does not lose on the spot, but it is bad enough, so that good players don't play this opening with black.

There is a similar opening, the Grunfeld. 1. d4 Nf6 2. c4 g6 3. Nc3 d5 which is much better, because there are good ways to immediately attack white's pawn center.

@Cruxo but the strongest players don't play c xd5, why if its bad for black ? And strong players play that with black. But textbooks if i recall correctly say its bad.

In the Lichess book, cxd5 is the most played move.

@Cruxo in the ct database the strongest to play cxd5 is 2730, the strongest to play nf3 is 2880. And nf3 gets played way more often

Because white wins after cxd5

@OnkelOnkel than why is the 2880 player playing nf3 instead? A 2880 player.

@OnkelOnkel why is according to ct nf3 a more popular move for gms?

Nf3 transposes into normal Queen's Gambit lines.
Maybe they don't want to punish their opponent for the inaccuracy because they fear to run into some preparation. But I don't know.

According to my own understanding and experience, cxd5 is best.

What games are you referring to?

@Ihavenothing Nf3 isn't played more commonly, If you had half a brain you would recognise that chessbase doesn't follow variations, it only knows positions

1.d4 d5 2.Nf3 Nf6 3.c4 is an actual way to play for black and can be transposed into by 1.d4 d5 2.c4 Nf6 3.Nf3

Click on the games and none of them will begin d4 d5 Nf6