Darklink401
Smash Master
I can see that.Doing it once isn't hard for an experienced player. Doing it over and over and over and over and over (etc) again in a match is harder, and more strenuous, than most other inputs in Melee.
I guess doing it repeatedly from side to side would be simplistic, but doing it quickly enough for it to be effective, to the level that these top players use it, and in such dynamic ways (especially after years of doing so) WOULD likely be very taxing XP