How could a VBT do a better job than two separate pots for hum control ?
A blend pot is basically two pots in the same case, nothing more. The signals of the two pickups will sum up (differentially because the pickups are at opposite phase), depending on their relative volume (= position of their volume pot track), it’s exactly the same with two volume pots or one blend pot.
This post can be an interesting reading 
: Blend pot : how and why?