...And why are you surprised?
All of the pokemon you've highlighted either don't have a niche in OU, be it for one reason or another, or their respective niches and roles in the metagame aren't as valueable as those that other pokemon offer in the tier. It should be of no surprise to anyone who knows the tier well enough to know that things like scizor and conkeldurr barely rack up enough usage in the tier, and their (un)rankings on the
VR should only be a testament to this, especially when the highest rank of any of the mons you highlighted is a whopping
C.