Not exactly sure if this is an oversight because I know absolutely nothing about the sicilian, and it has been played more than 100 times in my database (with a terrible score though). But it seems to me white basically loses a pawn for almost no compensation other than a slight dark square weakness.
Nakamura does fight back and gain the pawn and some initiative, but loses in the end.
here's the position after white's 8.Nb3, black to move:
I don't play that kind of sicilian either, but I remember watching this game and the commentator (larry christiansen?) saying Nb3 was a well-known error in the opening.
I tried looking for the video on ICC but can't find it. I thought it was one of the GOTDs from the NH chess tournament, but apparently not?
ah scratch that, found it, it's in the beginning of the round 6 smeets vs. beliavsky GOTD video. - the problem was naka got his move order mixed up, he should've castled first before Nb3.
