What's the deal with slapping Assault Vest on everything?

AV is a terrible item, literally the only pokemon that's good with it is Conkeldurr, as it has a rare mix of priority, reliable recovery and way to boost its attack.

Other than that it sucks, forcing you to only use attacking moves hurt you more than it helps, especially if you play VGC where Protect is crucial. Leftovers is better in every situation.