User blog comment:Plexioth- xD/Monster Hunter 3 Ultimate/@comment-7001294-20130212033913/@comment-1837917-20130212082107

No one's forcing you to use Brachydios weapons, or slime weapons for that matter. They're popular for speed running more than anything.

The popularity of the Kelbi Bow may also be due to the fact that, once awakened, its Slime Element is 150 points above Brachydios' own final bow. (Brachydios Final Bow; 312 Raw, 200 Slime)

And @Shogun Kirin, that skill was unique to White Fata Z armour back in MHFU, I wouldn't have a clue what armour has it now.