Valvoline does need to do something with their mid range product. MaxLife and SynPower get all the attention, market-wise and likely formulation-wise too. Maybe they are happy with the way VWB, ML and SP are selling and they don't push the DB at a retail level. ML is sort of their mid-range product anyway.
It is kind of strange, I believe most oil companies struggle with sales of the Hi-Miles and Blend products. We get things like Truck & SUV "Blend" and stuff like that. I never really buy that stuff unless it's on closeout. MaxLife basically cornered the Hi-Miles market.
fwiw, I used DB quite a few times before coming to BitOG, back in the '90s. I knew SP was a good product, and also knew instead of plain dino oil, a few bucks extra for the DB was probably worth it. In hindsight, SJ and SL dinos were not too great. DB had the A1 rating that others didn't at the time.