which IS IT
it is dashdancing. you did not perform what was in the video (which covers more space than what you did + has about the same functionality as dashdancing)
i think people saying it's not dashdancing basically mean "well, yeah, it is dashdancing, but it doesn't have any real use unlike actual (64/melee/PM) dashdancing"
it's similar to people saying "you can't combo in brawl and smash 4"
well yes, you can combo, but combos are few, short, unreliable, or only a few characters have them
but compare to 64 where high hitstun, no DI, and instant meteor smashes means 0-to-deaths are common, or melee/PM where mobility lets you techchase and react to DI more easily and you can't airdodge out of tumble like in brawl smash/4