because v simply, every1 wud quickly learn how to get it every time, and that wud render the game obsolete.

I potted 9 from break once, but the balls glitched and moved, and it took the ball out of the pocket

(had this glitch quite a lot)

The break cannot be repeated over and over as the ball is slightly replaced in a different spot each game, the only possible way to repeat the '9 in-off break' would be to find out how many games are in between each time the cue ball is placed in the same place - virtually impossible.

oh rite,
well i was jus having an educated guess, i never go on 9-ball cos i find it boring and the rules are daft, but ty 4 pointing this out to me :)

The thing was there never used to be so many possible outcomes of a break, and people learnt to do it every time, so fod had to change it.