NES Tetris predates the bag rule. The RNG is an 8-sided die with one side meaning "reroll", so it is basically random. That's how you can easily get into drough

NES Tetris predates the bag rule. The RNG is an 8-sided die with one side meaning "reroll", so it is basically random. That's how you can easily get into droughts of I-pieces for long enough to end a run, and this greatly influences top-level play to encourage "burning" L- and T- pieces instead.