It helps when you use the Game Editor and can see the results of your moves.
The problem is that white is still at a disadvantage after your sequence of moves. White hasn't achieved anything. It's blacks turn to move. Material is equal and no pieces are developed and it's black's turn. That means that white gave up his opening advantage for nothing.
And most people won't play your favorite sequence. They will play other moves like 3.. N6 and 4..h6 leaving you even worse.
Why play such a system? I challenge you to go back and look at your game history and see how many games you won and how many you lost with this system.
Early deployment of the Grob is inferior to variations of transpositions from other openings characterised by closed positions. 1 g4 d5 2.g5 e5 3, a3 d8g5 4, d4 g5d8 5. de represents my favorite spike variation