I heard that there are some glitches involving Ariel turning around to cancel her throwing animation(For example, to do a "Bubble cancel" you press backwards + A on the same frame, then quickly hold forward to keep running. Could be useful on some stages where you're forced to bubble, like Stage 2. There is a "Quick backthrow" too, which is done with an item. The input is the same, but you can use diagonals to throw. Not sure if it would be useful on the run somehow, but I tested on an emulator, and everything works). Would that be allowed on a run? If it is, I think someone could beat the WR(Or the holder could get a better time, don't know).
A lot of those throws are just really difficult to perform is all. and there is still so much time on the table from getting a better pattern set with execution, but I wouldn't say the game couldn't go in that direction.