The bead sort is a really smartass solution that could be considered an instructional example of the benefits of parallelization as well as exploitation of situational advantages.

Gravity effectively gives infinite free "threads" for the falling and it engages in accounting tricks with assumptions - normally the starting state set up is taken for granted because either it is already there or would always have to be done the same way (no getting around reading in the N numbers) which is more involved in a physical system.

I liken it to being asked to give the value of pi and giving the answer as a red circle split by a green line in the center and writing length of red divided by the length of green. Technically correct and efficient in calculations but extracting it involves more work not in the solution.