Anything can work once in a while if your opponent isn't prepared. The Grob only catches people sometimes because it is so bad they don't expect it and can fall into a couple of traps, especially in faster time controls.
But hey everyone has fun their own way with this game. If you want to grab a few wins here and there and not improve your game much, the Grob surely will entertain for a while. If you are already at master level then, well, you can play whatever you like lol.