why do most people play dxc6 in the Nyezhmetdinov-Rossolimo where white takes the knight?

I honestly think that its better to take with the b-pawn.

Taking with the d pawn opens lines for the queen and bishop

i think that bxc6 is better because it make your pawns more centralized

Open lines and piece development are usually more favorable than pawn structure in the opening.

If I knew what you were talking about I'd respond but seeing as I don't play the old classical sicilian...

1. e4 c5 2. Nf3 Nc6 3. Bb5 a6 4. Bxc6 dxc6 (@ukrainiandude wants to know why dxc6 is played and not bxc6)

I also don't play the Sicilian, but this is the line I usually play against it

probably because of ez development

I'd take development over pawn structure anytime

"Nyezhmetdinov-Rossolimo?"

What on earth is that? Someone tell me if I am terribly ignorant...

Well if some russian dude and some russian dude came together and the first one improved on the second's line, then you'd get something like that.

lol