Why do throwing athletes deliberately step over the foul line?

Answer 1

If they have thrown a disappointing distance which does not meet up to their expectations, and they know they can do better, they may step over the line so the distance is not recorded and a "No throw" is recorded instead.

Answer 2

Some Baseball players believe if you step on the foul line intentionally it is bad luck so it is mainly just superstitious.

Answer 3

pure superstition