And for whatever it's worth, my kneejerk dismissal of the lowbrow dismissal is just as valid a contribution to the conversation. So, good day to you.
I agree the rollover to level 0 would be the ultimate milestone, if it really resets to the beginning and doesn't introduce a bunch of new challenges and crash conditions. But this would be a much less satisfying milestone, as it just leads to the endurance-fest of being able to play until your physical/mental stamina is exhausted.
You can still get a higher high score before crashing it and have other achievements. But as far as beating the game by not going game over I think that goal has been reached.
The definition of "beating" the game is simply a convention.
At around level 247, you start to get game crashes without clearing any lines, just because the 'wrong' kind of piece appeared.
Now try to clear a bunch of lines with restrictions on what kind of pieces are allowed to randomly spawn.