Who thinks this is a Sicilian?

FTB copied these quick 1.Nf3 w/delayed c4 lines from another site.

Catalan QGD: 1 Nf3 d5 2 g3 Nf6 3 Bg2 e6 4 O-O Be7 5 c4 O-O 6 d4 dxc4

Fianchetto KID: 1 Nf3 Nf6 2 g3 g6 3 Bg2 Bg7 4 O-O O-O 5 d4 d6 6 c4

Fianchetto Gruenfeld: 1 Nf3 d5 2 g3 g6 3 Bg2 Bg7 4 d4 Nf6 5 O-O O-O 6 c4 dxc4

QID: 1 Nf3 Nf6 2 g3 b6 3 Bg2 Bb7 4 O-O e6 5 c4 Be7 6 d4

Dutch: 1 Nf3 f5 2 g3 Nf6 3 Bg2 g6 4 O-O Bg7 5 d4 O-O 6 c4 d6

White does avoid a few Black defenses, especially those based on concrete central pawn stuff (e.g. Albin, Budapest, QGA, Noteboom, Nimzo, Benonis, Benko), but I don't think the main advantage of Nf3+g3 is in restricting Black's options. Black has plenty of choice, including quite a few extra options not available via the 1. d4 2. c4 move order, such as:

1 Nf3 c5

Reversed Gruenfeld: 1 Nf3 d5 2 g3 c5 3 Bg2 Nc6 4 d4 Nf6 5 O-O e6 6 c4 dxc4

Slav (with the LSB developed): 1 Nf3 d5 2 g3 Nf6 3 Bg2 c6 4 O-O Bg4 (or Bf5)

"Extended" QID: 1 Nf3 Nf6 2 g3 b5
Reversed Veresov: 1 Nf3 d5 2 g3 Nc6 3 d4 Bg5 4 Bg2 Qd7

If allowing these bothers you, then a d4+Nf3 move order might be preferable.

Perhaps the real point of Nf3+g3 is that White gets extra flexibility, and can steer towards a KIA or English instead at any point. If you have some ideas along those lines, then you give yourself more of a reason to not play d4 on move 1.

Kramnik has experimented with every possible move order to reach these positions. Yet it doesn't really work if black answers with 1...c5 or plays a slav setup with Bf5. If you start with Nf3 you get in c4 too late and if you start with c4 you have to face 1...e5. Unfortunately there is no best of both worlds.

After 1 Nf3 b5 2 e4 Bb7 3 Bxb5 Bxe4, Stockfish gives +0.9 for both 4 d4 and 4 O-O.

****