about the manga source not sure just heard it in the anime. not here to prove a theory just bring up the idea that one might be wrong
Found a article and link..
Members of this clan were very knowledgeable in the art of fūinjutsu, and were both respected, and feared worldwide because of their prodigious skill. Though noted to be crude in their methods, this however, eventually led to the destruction of Uzushiogakure and the rest of the Land of Whirlpools during the era of Shinobi World Wars, as other nations had begun to see the village as too great a threat to go unchecked.
You must be registered for see links
Crude
1. Being in an unrefined or natural state; raw.
2. Lacking tact or taste; blunt or offensive: a crude, mannerless oaf; a crude remark.
3. Characterized by uncultured simplicity; lacking in sophistication or subtlety: had only a crude notion of how a computer works.
4. Not carefully or skillfully made; rough: a quick, crude sketch.
5. Undisguised or unadorned; plain: must face the crude truth.
6. Statistics In an unanalyzed form; not adjusted to allow for related circumstances or data.
7. Archaic Unripe or immature.
Not what i expected but kinda sounds like Naruto is at times