It's to reduce potential target size of oneself and increase accuracy of one's own shots whilst being in such a reduced size.

Thank you Remington for the info. Another question if you don't mind ... does that change the accuracy/speed of your aim or does it just depend on how you train/practice?

It's used for close contact shooting and get better with practise Books.

Shooting someone further away would require more accuracy and so extended arms and line of sight would need to be improved.

It's a precautionary stance for when you are in unknown territory and combatants could be anywhere around you.