The Grob ... why

So I posted a form asking what is the best opening at the sub 800 level and there seems to be a handful of 600s really advocating for the grob. I just want to know why as I read their reasons and it still made no sense. 

~Grob Mainline I think :

I just want to hear someone fight for this lol

The only advantage I can see is hoping black blunders their queen's rook as a result of your long diagonal bishop. Otherwise seems like a really terrible opening.

You don't have to believe everything you read on the internet. Especially not chess advice from 600 rated beginners.

Apparently if you play the Grob you end up having a rating around 600. A bit more seriously, objectively the Grob is not a good opening. The only advantage it has is that most players are unfamiliar with the positions and might blunder. If you know the ideas well, you can get an equal position (or an advantage if Black blunders), but usually just by using natural development Black is fine.

The problem with 1. g4 is that you are committed to a kingside attack before you know anything about your opponent's plans. You are also making kingside castling dangerous (often h3 needs to be played and there are quite big holes in the kingside) and giving Black better control over the center. If you definitely want your bishop on g2, 1. g3 is a better option. It also does not contain much theory, but the downside is that have to adapt to whatever plans Black has and your position may get a bit cramped by Black's central control. Still for beginners I would prefer any mainline e4 or d4 opening to g3.

What about the kingside fianchetto opening?

Maybe the point of grob is to distract with the pawn captures?

Maybe there was some form of karma involved, but pretty much straight after I said the Grob is not a good opening, I had to face it in a daily game against an opponent about 250 points higher rated than I am. He apparently likes to play the Grob against lower rated opponents and has a good win rate with it. Nevertheless, I managed to win the game so I can still say that the Grob is not a good opening.

I read once that Grob himself played a ton of correspondence games with it. I don't know if he succeeded.

You're not going to be seeing the grob in master level games, but honestly, your accelerated Sicilian dragon at a 900 rating isn't going to be resembling a master level game, either.

The grob brings an open tactical game, which is what you want U1200.  If a person develops without really thinking about their opponent's threats(which is a lot of U1000 players, honestly), it has a built in attack. 

Plus, I've found that U1000's kind of fall apart once they see an opening that isn't 4d, 4e.

The Grob is 1. g4, it covers more than the line in the original post. Reasons to play the Grob would be that you play well in open, tactical games and if you are really booked up, there are opportunities to really punish your opponent's mistakes. It's certainly playable (IM Baseman champions it), but as others have said, it's objectively a poor opening.

There was this guy at my old club who was probably the most timid player I've ever known. He was probably 1700-1800, but never attacked and only liked super quiet, slow games in openings that he was comfortable in. I ended up getting paired with him in a tournament one day back when I was around that same level, and was looking to surprise him. So what I do play? The grob! The guy practically crapped his pants when he saw 1. g4, and got so flustered and bewildered that I beat him in like 20 moves.

On another occasion, I played a guy who only ever played the kings indian attack as white. So I answered with 1... h6 and 2 ...g5. That guy spent the next few moves getting so worked up over the idea of that g pawn messing with his knight that he ended up playing all these silly prophylactic moves against it, like h3 and even Nf3-Nh2. He pretty much forgot all his plans, got bamboozled, and I ended up steamrolling him pretty easily.

So there's definitely a place for openings like that. I wouldn't play it against 600 level beginners though. They haven't built up enough dogma for the psychological blow to land properly. It works best against 1400-1700 players. Objectively, yeah, it sucks. But you're not playing the board - you're playing the person behind the board, and 1g4 is pretty much the same at cussing them out on move one. That can really throw someone off their game. Don't try it against a computer though! But against a human, who has emotions and the ability to blunder, sure, go for it. I've never lost a tournament game playing it for either white or black. Just don't make it your main opening.

Is the Grob opening objectively sound? Of course not! Does that mean we should discount it as a decent opening? Absolutely not! Even though it is objectively refuted, it has a ton of theory and has many tactical tricks in it; this opening carries a lot of surprise value and is a great weapon against the right unprepared opponent as @earikbeann commented

I hardly ever see the Grob opening by any rating (been a long time since I played 600s though), but there is someone at my local chess club (rated around 2000 OTB rating) who sometimes uses it in off-hand games to solid success. I'm sure they are not alone, I've heard several people online use that opening occasionally too. 

In my opinion, there are certainly better (and more solid) openings White could choose from, but because so many players are unprepared to face 1. g4, it might hold more merit than it should because many don't "do their homework" on this opening.

I would not recommend this opening to anyone under 1500 rating though; not only does this opening violate opening principles, but it is also surprisingly positional as well as tactical in some lines and quite simply put, a 600 player lacks the understanding to use this opening effectively - all they will do is play a few moves out of an objectively bad opening and give the opponent a chance to exploit them by following basic opening principles. 

The Grob has not been refuted. There are lines where black gets early equalization, but nothing where black is objectively better than white. 

Do you mind sharing with me your source on this? With all due respect, I am virtually certain this opening has been refuted (granted, it might take 20 moves of accurate play in all variations xD). 

Double grob

It is typically better to just follow opening principles and play solid chess. This is even more true when the opponent violates opening principles like with 1. g4? If you continue with 1...g5?? then you are justifying White's move one mistake because you now voluntarily expose your Kingside just as White has done. 

If you don't have a memorized repertoire or "book opening" response to something like 1. g4, then you are probably best playing solid. This probably means 1...d5 and developing pieces. Knights to f6 and c6 and Bishops developed out. When you learn more theory, then you may opt for other piece locations (such as ...Nbd7 and pawn ...c7-c6 to hinder the g2 Bishop scope).

I do play the grob myself from time to time. But in all honestly, I lose more often with it than I win. Standard game plans are simle, put pressure on the D5 and B7 pawns with queen and bishop and push the G pawn in the face of the f6 knight if your opponent dares to place it there. You rarely castle king side, either queen side and sometimes you kings stays in the middle or goes to F1.

It's not sound but it's a lot of fun to play for me. You can use it create a wild game with uncommon structures.