Demon Slayer: Kimetsu no Yaiba

[Buffalobiian]

What makes you think they're incomplete?

Tanjiro is shit at it, but that doesn't mean the techniques are incomplete.

I don't think you should expect one to kick demon once you know Sun Breathing, let alone practicing it by remembering your dad's moves as a kid.

Trainers of different styles send their kids to the exam, some die, some become mediocre and a few become Hashira. Tanjiro sucking at Sun doesn't make it inherently incomplete or bastardized.

Actually, the fact that it's been passed down as a slow dance but when executed in combat becomes a real move (after recognising its true nature as a combat art) suggests that it is the real thing.

Pass it down as a dance. Those who can make it work, will. As opposed to passing it down as a combat art, and those who can't make it work forget or tweak it into something else to maintain proficiency.